Cardiovascular changes in pregnancy � Obstetrics Paper 1 Prelim Compilation By H.G!!.pdf Principle of urine pregnancy test � Obstetrics Paper 1 Prelim Compilation By H.G!!.pdf 4 indications of USG in pregnancy � Obstetrics Paper 1 Prelim Compilation By H.G!!.pdf Grades of placenta previa 4 causes of cervical incompetence Pritchard regimen External cephalic version AMTSL Differential diagnosis/management of puerperal fever GDM screening VBAC/TOLAC definition Shoulder dystocia Neonatal resuscitation 4 direct causes of maternal mortality Reassuring NST Oligohydramnios Anti-D prophylaxis Conservative/expectant/medical management of ectopic Clinical features of molar pregnancy Induction of labour Fetal circulation Misoprostol uses

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📚 Obstetrics Paper 1 - Prelim Compilation

1. Cardiovascular Changes in Pregnancy

Parameter	Change	Magnitude
Blood volume	Increases	40-50% (plasma > RBC = physiologic dilutional anaemia)
Cardiac output	Increases	30-50% (peaks at 28-32 weeks)
Heart rate	Increases	10-20 bpm above baseline
Stroke volume	Increases	Due to increased preload
SVR (systemic vascular resistance)	Decreases	Due to progesterone-mediated vasodilation
Blood pressure	Decreases in 1st & 2nd trimester	Rises back to baseline in 3rd trimester
Colloid oncotic pressure	Decreases	Due to dilutional hypoalbuminaemia

Positional effects: Supine hypotension syndrome - aortocaval compression by gravid uterus in supine position; relieved by left lateral tilt.

ECG changes in pregnancy (physiologic):

Sinus tachycardia
Left axis deviation
Inverted T-waves in lead III / aVF
Non-specific ST changes

Auscultatory changes:

Systolic flow murmur (S1 louder, exaggerated splitting)
S3 may be heard (normal in pregnancy)

2. Principle of Urine Pregnancy Test

The urine pregnancy test is based on immunological detection of beta-hCG (human Chorionic Gonadotropin).

Principle: Uses a monoclonal antibody sandwich ELISA / lateral flow immunoassay:

hCG is secreted by syncytiotrophoblast from day 8-10 post-fertilisation (day 1 of missed period)
Anti-hCG antibodies (conjugated to a dye/enzyme) bind hCG in urine
The antigen-antibody complex migrates along the nitrocellulose strip
Captured by a second immobilised anti-hCG antibody at the test line → visible band = POSITIVE

Sensitivity: Can detect hCG as low as 20-25 mIU/mL Earliest positive: ~4 weeks gestation (1 week after missed period) False positives: Molar pregnancy, choriocarcinoma, cross-reaction with LH False negatives: Very dilute urine, hook effect (extremely high hCG, as in molar pregnancy - prozone phenomenon)

3. Indications of USG in Pregnancy (4 Main)

First trimester (6-14 weeks):
- Confirm intrauterine pregnancy and viability
- Determine gestational age (CRL - crown rump length, most accurate)
- Detect multiple pregnancy
- Nuchal translucency screening (11-13+6 weeks) for chromosomal anomalies
Second trimester (18-22 weeks - Anomaly scan / TIFFA):
- Fetal anatomical survey for structural anomalies
- Fetal biometry (BPD, FL, AC, HC)
- Placental localisation and liquor assessment
Assessment of suspected fetal growth restriction (FGR) / IUGR:
- Serial growth scans + Doppler studies (umbilical artery, MCA)
Third trimester / specific obstetric indications:
- Confirm fetal presentation (especially before ECV or induction)
- Assess placenta previa
- Biophysical profile (BPP) for fetal wellbeing
- Unexplained antepartum haemorrhage (APH)
- Suspected polyhydramnios/oligohydramnios

4. Grades of Placenta Previa

(Macafee / Traditional Classification - 4 grades)

Grade	Description
Grade I (Low-lying)	Placenta in lower segment but does not reach the internal os
Grade II (Marginal)	Placenta reaches but does not cover the internal os
Grade III (Partial)	Placenta partially covers the internal os
Grade IV (Central / Complete)	Placenta completely covers the internal os

Modern classification (2-type system, preferred by RCOG/FIGO):

Minor: Grades I & II (low-lying + marginal)
Major: Grades III & IV (partial + complete)

Key clinical point: Grade IV (complete central) = always LSCS; vaginal examination contraindicated (no PV/PR exam).

5. 4 Causes of Cervical Incompetence

Cervical incompetence (cervical insufficiency) = painless cervical dilation in second trimester without contractions.

Congenital / structural weakness:
- Congenital short cervix
- Mullerian duct anomalies (uterine septum, bicornuate uterus)
- DES (diethylstilboestrol) exposure in utero (causes T-shaped uterus and hypoplastic cervix)
Traumatic / iatrogenic injury:
- Forceful cervical dilation (D&C, D&E, ERPC)
- Cervical lacerations from previous difficult deliveries
- Cone biopsy / LLETZ (loop excision) for CIN
Connective tissue disorders:
- Ehlers-Danlos syndrome
- Marfan syndrome
Functional / hormonal:
- Progesterone deficiency
- Relaxin excess

Management: McDonald's or Shirodkar cervical cerclage (suture at 12-16 weeks); vaginal progesterone

6. Pritchard Regimen (Magnesium Sulphate for Eclampsia)

The Pritchard regimen is the most widely used protocol for management and prevention of eclamptic fits.

Loading Dose:

4g MgSO4 IV (20% solution, over 5-10 minutes)
PLUS 10g MgSO4 IM (50% solution - 5g deep IM in each buttock)

Maintenance Dose:

5g MgSO4 IM (50% solution) into alternate buttocks every 4 hours
Continue for 24 hours after last fit OR after delivery (whichever is later)

Monitoring before each dose (STOP if any absent):

Urine output ≥25 mL/hour
Respiratory rate ≥16/min
Knee jerk (patellar reflex) present

Antidote for toxicity: Calcium gluconate 1g IV (10 mL of 10% solution) slowly

MgSO4 toxicity levels:

Therapeutic: 4-7 mEq/L
Loss of reflexes: 7-10 mEq/L
Respiratory paralysis: 10-13 mEq/L
Cardiac arrest: >15 mEq/L

7. External Cephalic Version (ECV)

Definition: Manual, external rotation of a breech/transverse fetus to cephalic presentation through the maternal abdominal wall.

When performed: 36-37 weeks gestation (after 36 weeks for nulliparous; 37 weeks for multiparous)

Prerequisites/Conditions:

Non-engaged breech presentation
Adequate liquor
No contraindications
Informed consent

Contraindications:

Previous LSCS (relative - increasingly done in selected cases)
Placenta previa
Oligohydramnios
Multiple pregnancy
Fetal anomaly
APH in current pregnancy
Abnormal CTG / fetal compromise
Uterine anomaly
Pre-eclampsia

Pre-procedure: Tocolysis (terbutaline 0.25mg SC); confirm with ultrasound; IV access; CTG baseline

Technique:

Displace breech from pelvis
Forward roll (or backward somersault if failed)
Continuous CTG monitoring

Success rate: ~50-60% (higher in multiparae, adequate liquor, transverse lie)

Complications: Placental abruption, premature labour, cord prolapse, feto-maternal haemorrhage (give Anti-D if Rh-negative), emergency LSCS

8. AMTSL (Active Management of the Third Stage of Labour)

AMTSL reduces PPH risk by 60-70% and is the standard of care.

Components (WHO 2012 - 3 components):

Uterotonic administration (MOST important) - Oxytocin 10 IU IM within 1 minute of delivery of anterior shoulder (preferred) OR after delivery of baby
Controlled cord traction (CCT) / Brandt-Andrews technique - with uterine counter-pressure (only after uterus contracts)
Uterine massage after placenta delivery (uterine tone assessment)

Note: WHO 2012 removed cord clamping timing from AMTSL definition; early cord clamping is no longer recommended - delayed cord clamping (1-3 min) is now advocated.

Alternative uterotonics (if oxytocin unavailable):

Misoprostol 600 mcg orally
Ergometrine 0.2mg IM (not in hypertension)
Carbetocin 100 mcg IM (single dose, longer acting than oxytocin)

9. Differential Diagnosis and Management of Puerperal Fever

Definition: Temperature ≥38°C on any 2 of the first 10 days postpartum (excluding first 24 hours), measured orally.

Differential Diagnosis - "The 5 W's" mnemonic:

Day	Cause	Mnemonic
Day 1-2	Wind - Atelectasis, aspiration pneumonia, pneumonia	Wind
Day 2-3	Water - Urinary tract infection (UTI, catheter-related)	Water
Day 3-5	Wound - Episiotomy/perineal wound infection, LSCS wound infection	Wound
Day 5-7	Womb - Endometritis / endomyometritis	Womb
Day 7-10	Walking - DVT / pelvic thrombophlebitis	Walking

Other causes: Mastitis/breast abscess, infected haematoma, septic thrombophlebitis

Management of Puerperal Sepsis:

Investigations: FBC, CRP, blood cultures, urine C&S, wound swab, HVS
Sepsis 6 protocol if septic shock (blood cultures → IV antibiotics within 1 hour → IV fluids → oxygen → urine output monitoring → lactate)
Endometritis: IV Ampicillin + Gentamicin + Metronidazole (triple antibiotic therapy); oral Amoxicillin-clavulanate after improvement
Wound infection: debridement + antibiotics
DVT: LMWH (enoxaparin)
Mastitis: Flucloxacillin + continue breastfeeding; if abscess → incision & drainage
Septic abortion: IV antibiotics + uterine evacuation

10. GDM Screening

Gestational Diabetes Mellitus (GDM) Screening

Universal screening (WHO 2013 / IADPSG criteria) - Gold Standard: 75g Oral Glucose Tolerance Test (OGTT) at 24-28 weeks

GDM diagnosis if ANY ONE value met or exceeded:

Time	Glucose threshold
Fasting	≥5.1 mmol/L (92 mg/dL)
1 hour	≥10.0 mmol/L (180 mg/dL)
2 hours	≥8.5 mmol/L (153 mg/dL)

High-risk women - screen earlier (first trimester):

Previous GDM
BMI >30
Previous macrosomic baby (>4kg)
Family history of type 2 DM (1st degree)
PCOS
Glucosuria on dipstick

Earlier screening: HbA1c or FPG at booking visit; if abnormal → overt diabetes in pregnancy

Management of GDM:

Medical nutrition therapy (MNT) + exercise for 2 weeks
If targets not met → Metformin (first-line oral agent) or Insulin
Fetal surveillance: growth scans at 28, 32, 36 weeks; Doppler if FGR
Deliver at 38-39 weeks (if well-controlled on diet); 37-38 weeks if on insulin/oral agents
Postpartum: 75g OGTT at 6-12 weeks to screen for type 2 DM

11. VBAC / TOLAC - Definitions

TOLAC (Trial of Labour After Caesarean):

The attempt at vaginal delivery in a woman with a previous caesarean section
It is the process/attempt

VBAC (Vaginal Birth After Caesarean):

The successful vaginal delivery in a woman who has had a previous caesarean section
It is the outcome

Eligibility for TOLAC:

1 previous LSCS with low transverse uterine incision
No other uterine scar or previous rupture
Clinically adequate pelvis
No contraindication to vaginal delivery
Facility for emergency LSCS available (immediate)

Contraindications to TOLAC:

Previous classical (vertical) uterine incision
Previous uterine rupture
Previous T-incision or inverted-T
Previous uterine surgery (myomectomy entering cavity)
≥2 previous LSCS (relative contraindication - centre-dependent)

VBAC success rate: ~60-80% (higher with previous vaginal delivery, spontaneous labour onset, favourable cervix)

Main risk: Uterine scar rupture (~0.5-0.9% with prior LSCS) Signs of scar rupture: Sudden fetal bradycardia, loss of fetal station, maternal tachycardia, abdominal pain, haematuria

12. Shoulder Dystocia

Definition: Failure of the shoulders to deliver spontaneously after the head has delivered, requiring additional obstetric manoeuvres. (Technically: head-to-body delivery interval >60 seconds, or need for ancillary manoeuvres)

Risk factors: Macrosomia, GDM, obesity, post-dates, previous shoulder dystocia, assisted vaginal delivery (forceps/vacuum)

Management - HELPERR Mnemonic:

Step	Action
H	Help - Call for help (senior obstetrician, neonatologist, anaesthetist)
E	Episiotomy - consider (gives more space for manoeuvres, not for the bony dystocia)
L	Legs - McRoberts manoeuvre (hyperflexion of maternal hips onto abdomen, flattens lumbar lordosis, rotates symphysis pubis upward)
P	Pressure - Suprapubic pressure (Rubin I - not fundal pressure)
E	Enter - Internal rotational manoeuvres (Rubin II: pressure on posterior aspect of anterior shoulder; Woods screw manoeuvre: pressure on anterior aspect of posterior shoulder)
R	Remove - Delivery of posterior arm
R	Roll - All-fours position (Gaskin manoeuvre)

Last resort (destructive/all-fours failed):

Deliberate clavicle fracture
Zavanelli manoeuvre (cephalic replacement) → emergency LSCS
Cleidotomy (deliberate fracture of clavicle in live baby - avoided)
Symphysiotomy

Documentation: Time of head delivery, time of body delivery, manoeuvres used, Apgar scores, umbilical artery pH

13. Neonatal Resuscitation

Initial assessment at birth (Apgar at 1 and 5 minutes): Assess: Colour, tone, breathing, heart rate

ABC of Neonatal Resuscitation (NRP/ILCOR 2020):

Step 1 - Initial steps (first 30 seconds):

Dry and stimulate (dry vigorously with warm towel)
Maintain temperature (warm environment, plastic wrap if <32 weeks)
Position: neutral neck position, sniffing position
Clear airway if needed (suction only if copious secretions blocking airway)

Assess: Breathing + Heart Rate

Step 2 - If apnoeic or HR <100 bpm:

Positive Pressure Ventilation (PPV): 40-60 breaths/min
Room air (21% O2) for term babies; 21-30% O2 for preterm
Check chest rise; if not moving: reposition, increase pressure (PEEP 5 cmH2O)
Use CPAP for breathing but inadequate in preterm

Step 3 - If HR <60 bpm despite 30 seconds adequate PPV:

Chest compressions: 3:1 ratio (3 compressions: 1 breath); 120 events/minute
100% oxygen
Consider intubation (ETT)
IV/IO access

Step 4 - If HR still <60 bpm:

Adrenaline (epinephrine): 0.01-0.03 mg/kg IV (0.1-0.3 mL/kg of 1:10,000)
If IV access unavailable: ET adrenaline 0.05-0.1 mg/kg
Normal saline 10 mL/kg if volume depleted/hypovolaemia

Step 5 - Post-resuscitation:

Continued monitoring of HR, SpO2, glucose
Therapeutic hypothermia (cooling) if ≥36 weeks with hypoxic-ischaemic encephalopathy (HIE): 33-34°C for 72 hours within 6 hours of birth

14. 4 Direct Causes of Maternal Mortality

(WHO / FIGO classification - direct obstetric causes)

Haemorrhage (most common globally) - PPH, APH (placenta previa, abruption), ectopic, molar pregnancy
Hypertensive disorders of pregnancy - Eclampsia, severe pre-eclampsia, HELLP syndrome
Sepsis / Puerperal sepsis - Endometritis, septic abortion, group A Streptococcus
Unsafe/Induced abortion - Haemorrhage, sepsis, trauma from illegal/unsafe procedures

Other direct causes:

Obstructed labour (uterine rupture, fistula)
Pulmonary embolism / thromboembolism (VTE)
Amniotic fluid embolism

(In high-income countries: VTE and cardiac disease are leading causes; in LMIC: haemorrhage and sepsis dominate)

15. Reassuring NST (Non-Stress Test)

A reactive / reassuring NST indicates normal fetal autonomic function (intact fetal CNS).

Criteria for Reactive (Reassuring) NST:

At least 2 accelerations in 20 minutes
Each acceleration: peak ≥15 bpm above baseline, lasting ≥15 seconds
Baseline FHR: 110-160 bpm
Baseline variability: 6-25 bpm (moderate variability)
No significant decelerations

Before 32 weeks gestation: Modified criteria apply - accelerations of ≥10 bpm for ≥10 seconds are acceptable (lower amplitude as immature sympathetic system)

Non-reactive NST:

No qualifying accelerations in 40 minutes (after vibroacoustic stimulation)
Requires further evaluation: BPP, contraction stress test (CST), or biophysical profile

Possible causes of non-reactive NST:

Fetal sleep cycle (normal - acoustic stimulation to wake)
Fetal compromise/hypoxia
CNS depression (magnesium sulphate, narcotics, betamethasone)
Prematurity

16. Oligohydramnios

Definition: Amniotic fluid index (AFI) <5 cm OR single deepest pocket (SDP) <2 cm

Normal AFI: 8-24 cm (5-25 cm by some definitions)

Causes (ARDS mnemonic):

A - Anomalies (fetal renal agenesis/Potter sequence, posterior urethral valves, renal dysplasia - most common congenital cause)
R - Rupture of membranes (PPROM/PROM)
D - Drugs (NSAIDs, ACE inhibitors - reduce fetal urine output)
S - Small for gestational age / IUGR (uteroplacental insufficiency - fetal oliguria)
Post-dates/post-term pregnancy
Idiopathic

Assessment: AFI on ultrasound; fetal anatomical survey (rule out renal anomaly); umbilical artery Doppler

Complications:

Fetal: pulmonary hypoplasia, limb deformities (Potter facies), umbilical cord compression
Obstetric: cord prolapse, meconium aspiration, IUFD

Management:

Identify and treat cause
Serial AFI monitoring
Amnioinfusion (during labour if cord compression causing variable decelerations)
Delivery at 37-38 weeks if at term with severe oligohydramnios

17. Anti-D Prophylaxis

Indications (Rh-D negative women):

Routine antenatal prophylaxis (RAADP):

500 IU Anti-D IM at 28 weeks (and 34 weeks if 2-dose regimen used)

After sensitising events:

Miscarriage / threatened miscarriage (>12 weeks) - 250 IU
Termination of pregnancy
Ectopic pregnancy
Amniocentesis / CVS / cordocentesis
External cephalic version
Antepartum haemorrhage (APH) at any gestation
Abdominal trauma in pregnancy
Intrauterine procedures / fetal blood sampling
Delivery of Rh-D positive baby - 500 IU within 72 hours of delivery
Manual removal of placenta

Kleihauer-Betke test: Done at delivery to estimate volume of feto-maternal haemorrhage (FMH) - if >4 mL fetal blood, additional Anti-D is required (500 IU covers up to 4 mL FMH; need 500 IU per additional 4 mL)

Principle: Anti-D immunoglobulin destroys fetal RBCs that entered maternal circulation before maternal immune system is sensitised, preventing Rh alloimmunisation and hemolytic disease of the newborn (HDN) in future pregnancies.

18. Conservative/Expectant/Medical Management of Ectopic Pregnancy

Ectopic pregnancy = Implantation outside the uterine cavity (most common: ampullary portion of fallopian tube ~70%)

Conservative (Expectant) Management

Criteria:

Asymptomatic patient (no pain, no haemoperitoneum)
Serum hCG <1500 IU/L (ideally <1000 IU/L) AND falling
Ectopic mass <3 cm on ultrasound
No fetal cardiac activity
Reliable patient who can attend follow-up

Process: Serial serum hCG every 48 hours until negative; if rising → switch to medical/surgical management

Medical Management - Methotrexate (MTX)

Criteria (ASRM criteria):

Haemodynamically stable
Serum hCG <5000 IU/L (some centres use <3000 IU/L)
Ectopic mass ≤3.5 cm (no fetal cardiac activity)
No contraindications to MTX
Compliant patient

Contraindications to MTX:

Haemodynamic instability
Breastfeeding
Immunodeficiency
Hepatic/renal disease
Blood dyscrasias
Fetal cardiac activity
hCG >5000 IU/L

Regimen:

Single-dose protocol: MTX 50 mg/m² IM (body surface area)
Monitor hCG on days 4 and 7; expect ≥15% fall from day 4 to day 7
If inadequate fall → repeat dose or surgery

Multi-dose protocol: MTX 1 mg/kg IM on days 1, 3, 5, 7 + Leucovorin (folinic acid rescue) 0.1 mg/kg IM on days 2, 4, 6, 8

Counsel: No NSAIDs, folic acid, alcohol, or UV exposure; avoid conception for 3 months

Surgical Management

Laparoscopic salpingotomy (conserves tube - if contralateral tube damaged/absent; higher risk of persistent ectopic)
Laparoscopic salpingectomy (removes tube - preferred if contralateral tube healthy)
Open surgery (laparotomy) if haemodynamically unstable

19. Clinical Features of Molar Pregnancy (Hydatidiform Mole)

Types:

Complete mole: 46XX (diploid, all paternal), no fetal parts
Partial mole: 69XXY (triploid), fetal parts may be present

Clinical Features:

Amenorrhoea + positive pregnancy test (hCG very elevated)
Vaginal bleeding (most common symptom) - brownish, prune juice-like; may contain vesicles ("grape-like" or "fish-roe" tissue)
Uterus large for dates (50% of cases) - due to molar tissue growth + theca lutein cysts
Hyperemesis gravidarum (severe nausea/vomiting) - from very high hCG levels
Pre-eclampsia before 20 weeks - classic "red flag" for molar pregnancy (early PET)
Theca lutein cysts - bilateral, ovarian (from hCG hyperstimulation); pelvic pain
Hyperthyroidism - hCG cross-reacts with TSH receptor; thyrotoxicosis symptoms (tremor, tachycardia, palpitations)
Respiratory symptoms - trophoblastic emboli (tumour emboli to lungs)
Absent fetal heart sounds (complete mole)
Snowstorm appearance on USG - classic "Swiss cheese" or echogenic mass filling uterine cavity with no gestational sac (complete mole)

hCG: Extremely elevated (>100,000 IU/L in complete mole) Management: Suction evacuation + histopathology; serial hCG monitoring; register with GTD centre; contraception for 6-12 months

20. Induction of Labour (IOL)

Definition: Artificial initiation of uterine contractions before spontaneous onset, with the aim of achieving vaginal delivery.

Indications (Common):

Post-dates pregnancy (≥41-42 weeks)
Gestational hypertension / pre-eclampsia
GDM (uncontrolled or at term)
PROM (premature rupture of membranes)
IUGR / fetal compromise
Cholestasis of pregnancy
Maternal medical conditions (renal disease, cardiac)
IUFD (intrauterine fetal death)

Prerequisites (Bishop Score): Assesses cervical favourability (dilation, effacement, consistency, position, station)

Favourable cervix: Bishop score ≥8 (or ≥6) → can proceed with amniotomy/oxytocin
Unfavourable cervix: Bishop score <6 → cervical priming/ripening first

Methods of IOL:

1. Cervical Ripening (unfavourable cervix):

Prostaglandins: Dinoprostone (PGE2) 1-2mg pessary/gel; Misoprostol (PGE1) 25-50 mcg vaginally/orally
Mechanical: Foley catheter balloon (30-60 mL), double balloon, hygroscopic dilators (Dilapan, laminaria)

2. Amniotomy (ARM - Artificial Rupture of Membranes):

Used when cervix is favourable (Bishop ≥6)
Stimulates PG release + presents presenting part onto cervix

3. Oxytocin infusion:

IV infusion, titrated to achieve 3-4 contractions per 10 minutes
Used after amniotomy or as primary augmentation

Contraindications to IOL:

Placenta previa
Previous classical uterine scar
Active genital herpes
Cord presentation/prolapse
Malpresentation (transverse lie)
CPD (cephalopelvic disproportion)

Complications: Hyperstimulation, uterine rupture, fetal distress, failed induction → LSCS, cord prolapse after ARM, infection

21. Fetal Circulation

Key features that distinguish fetal from postnatal circulation:

Fetal Shunts (3 physiological shunts):

Shunt	Location	Function
Ductus venosus	Connects umbilical vein to IVC	Bypasses liver; directs oxygenated blood to heart
Foramen ovale	Between right and left atria	Directs oxygenated blood from RA to LA (bypasses pulmonary circulation)
Ductus arteriosus	Connects pulmonary artery to aorta	Directs deoxygenated blood away from non-expanded lungs to systemic circulation

Fetal Circulation Flow:

Placenta → Umbilical vein (oxygenated) → Ductus venosus / Portal vein → IVC → RA → Foramen ovale → LA → LV → Ascending aorta → Brain/upper body

Some blood: RA → RV → Pulmonary artery → Ductus arteriosus → Descending aorta → Lower body → Umbilical arteries → Placenta

Key Points:

Umbilical vein carries the MOST oxygenated blood (from placenta)
Umbilical arteries (2) carry deoxygenated blood to placenta
Fetal haemoglobin (HbF) has higher O2 affinity than HbA (left shift of O2 dissociation curve)
High fetal PVR, low SVR (opposite of adult)

At Birth - Closure of shunts:

Foramen ovale: Closed by increased left atrial pressure (functional at birth, anatomical within days-months)
Ductus arteriosus: Closed by increased PaO2 + decreased PGE2 (functional 10-15 hours; permanent 2-3 weeks)
Ductus venosus: Closed by loss of umbilical venous flow (within 3-7 days)

22. Misoprostol Uses in Obstetrics & Gynaecology

Misoprostol is a synthetic PGE1 analogue (prostaglandin E1).

Obstetric & Gynaecological Uses:

Indication	Dose & Route
Cervical ripening / IOL	25 mcg PV 4-6 hourly; 25-50 mcg SL; 50-100 mcg PO
AMTSL / PPH prevention	600 mcg PO or 800 mcg SL (when oxytocin unavailable)
PPH treatment (refractory)	800-1000 mcg PR (rectal)
Medical management of miscarriage	400-800 mcg PV or SL (with or without mifepristone)
Medical termination of pregnancy (MTP)	Mifepristone 200 mg PO → 48 hrs later Misoprostol 400-800 mcg PV/SL/PO
Medical management of ectopic (adjunct)	Not first-line; rarely used locally
IUFD (intrauterine fetal death)	25-200 mcg PV every 4-6 hours (dose varies by gestation)
Cervical priming pre-surgical	200-400 mcg PV 3-4 hours before D&C/ERPC
Gastric ulcer prevention	200 mcg PO QID (original FDA indication - cytoprotection)

Side effects: Hyperstimulation, uterine rupture (if scar), diarrhoea, fever/chills (especially rectal route), nausea

Contraindications in IOL: Previous uterine scar (LSCS) - higher risk of uterine rupture compared to oxytocin

Compiled from standard obstetrics references including Williams Obstetrics, Dutta's Obstetrics, and RCOG/WHO guidelines.

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