Show me the complete screening algorithm and management plan for rhesu

Show me the complete screening algorithm and management plan for rhesus negative mothers from booking visit

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Rh-Negative Mothers: Complete Screening Algorithm & Management Plan

Background: Why This Matters

The D antigen of the Rh blood group system is the primary cause of Rh incompatibility. An Rh-negative mother carrying an Rh-positive fetus can have fetal red cells cross the placenta into her circulation, triggering maternal IgG anti-D antibody formation. In subsequent pregnancies, these antibodies cross the placenta and destroy fetal red cells, causing hemolytic disease of the fetus and newborn (HDFN) — manifesting as erythroblastosis fetalis, hydrops fetalis, jaundice, and kernicterus.

First pregnancies are usually safe because the primary immune response generates IgM (which cannot cross the placenta). The danger escalates with subsequent pregnancies: ~3% of 2nd babies are affected, ~10% of 3rd babies, and rising thereafter. — Guyton and Hall Textbook of Medical Physiology

Pathogenesis of Rh sensitization and immune hydrops fetalis

Pathogenesis of immune hydrops fetalis — Robbins, Cotran & Kumar Pathologic Basis of Disease

Screening Algorithm from Booking Visit

STEP 1 — Booking Visit (First Antenatal Visit, ~8–12 weeks)

Action	Detail
Blood group & Rh typing	ABO and RhD status must be determined for ALL pregnant women
Indirect Coombs Test (ICT) / Antibody Screen	Test for pre-existing anti-D (or other) antibodies in maternal serum
Partner blood grouping	Determine if father is Rh-positive (if Rh-negative father → fetus must be Rh-negative → no risk)

Interpret the antibody screen:

Antibody screen NEGATIVE + Rh-negative → Unsensitized → proceed with prophylaxis protocol below
Antibody screen POSITIVE (anti-D detected) → Already sensitized → escalate to alloimmunized pregnancy management

STEP 2 — Antenatal Monitoring (Unsensitized Rh-Negative)

Timing	Action
~20 weeks	Repeat ICT/antibody screen
28 weeks	Repeat ICT — if still negative, administer routine antenatal anti-D prophylaxis
34–36 weeks	Repeat antibody screen before second dose (where two-dose regimen used)

STEP 3 — Routine Antenatal Anti-D Prophylaxis (RAADP)

Who: All unsensitized (antibody screen negative) Rh-D-negative pregnant women

Dose & Timing:

Standard regimen: Anti-D immunoglobulin 300 mcg IM at 28 weeks (single-dose protocol — ACOG-endorsed)
Alternative two-dose: 100–125 mcg at 28 weeks AND 34 weeks

The anti-D antibody is given antepartum at 28–30 weeks of gestation. The mechanism involves clearing Rh-positive fetal cells from maternal circulation before B-lymphocyte sensitization can occur — thereby preventing formation of memory B cells that would activate in future pregnancies. — Guyton and Hall Textbook of Medical Physiology

Rh(D) immune globulin (300 mcg IM) is a concentrated solution of human IgG with high-titer anti-Rh(D) antibodies. For this prophylaxis to succeed, the mother must be Rh-D-negative and not already immunized. — Katzung's Basic and Clinical Pharmacology, 16th Edition

STEP 4 — Sensitizing Events Requiring Additional Anti-D Doses

Anti-D must be given within 72 hours of any potential fetomaternal hemorrhage (FMH), regardless of gestational age:

Sensitizing Event	Anti-D Dose
Miscarriage / threatened miscarriage	50 mcg if <12 weeks; 300 mcg if ≥12 weeks
Ectopic pregnancy	50 mcg (<12 weeks); 300 mcg acceptable
Chorionic villus sampling (CVS)	300 mcg
Amniocentesis	300 mcg
External cephalic version (ECV)	300 mcg
Antepartum hemorrhage (APH)	300 mcg; repeat if continued bleeding
Abdominal trauma	300 mcg — "If as little as 0.1 μL of Rh-positive fetal blood enters an Rh-negative mother's circulation, the mother can develop Rh antibodies" — Tintinalli's Emergency Medicine
Intrauterine procedures	300 mcg
Delivery of Rh-positive baby	300 mcg within 72 hours of delivery

ACOG and ACEP both recommend 50 mcg for procedures/events before 12 weeks (due to small fetoplacental blood volume ~4.2 mL at 12 weeks); 300 mcg for events at ≥12 weeks. — Tintinalli's Emergency Medicine

Kleihauer-Betke (KB) test / Flow cytometry: Performed when large FMH is suspected (e.g., trauma, significant APH, abruption after 12 weeks). Quantifies fetal cells in maternal blood — additional anti-D vials are given if FMH exceeds the coverage of 300 mcg (~30 mL fetal whole blood).

STEP 5 — Postnatal Management

Neonatal result	Action
Baby Rh-positive, mother still unsensitized	Give anti-D 300 mcg IM within 72 hours of delivery
Baby Rh-negative	No anti-D required
Large FMH on KB test	Additional anti-D doses proportional to estimated hemorrhage

Management of the Sensitized (Alloimmunized) Rh-Negative Mother

When anti-D antibodies are already present at booking or develop during pregnancy, prophylaxis is futile and management shifts to fetal surveillance:

Monitoring Protocol for Alloimmunized Pregnancy

Anti-D Titer	Management
Low titre (<1:4–1:8)	Serial antibody titres every 4 weeks; fetal surveillance with growth scans
Rising titre (≥1:16 or critical titre)	Doppler assessment of fetal middle cerebral artery peak systolic velocity (MCA-PSV) every 1–2 weeks
MCA-PSV >1.5 MoM	Strongly predictive of fetal anemia → proceed to fetal blood sampling (FBS)

Fetal Blood Sampling (FBS) & Intrauterine Transfusion (IUT)

FBS via cordocentesis (umbilical vein) confirms fetal hemoglobin
If fetal Hb <2 SD below mean for gestational age → Intrauterine intravascular transfusion (IVT) with O-negative, CMV-negative, irradiated, leukodepleted blood
May be repeated every 2–4 weeks until fetus is mature enough for delivery

Delivery Timing

Unaffected or mildly affected fetuses: Deliver at 37–38 weeks
Severely affected or post-IUT: Deliver at 34–37 weeks depending on fetal condition
Post-delivery: neonatal exchange transfusion and/or phototherapy for jaundice/hyperbilirubinemia; monitor for kernicterus

Antenatal identification and management of the at-risk fetus have been greatly facilitated by amniocentesis and chorionic villus and fetal blood sampling. Severe intrauterine hemolysis may be treated by fetal intravascular transfusions via the umbilical cord and early delivery. — Robbins, Cotran & Kumar Pathologic Basis of Disease

Complete Algorithm Summary

BOOKING VISIT
    │
    ▼
Blood group + Rh typing + ICT (antibody screen)
    │
    ├─── Rh POSITIVE ──────────────────► Standard antenatal care
    │
    └─── Rh NEGATIVE
              │
              ├─── ICT POSITIVE (anti-D present)
              │         │
              │         └─► ALLOIMMUNIZED pathway:
              │              • Serial titres q4 weeks
              │              • MCA-PSV Doppler if titre ≥ critical level
              │              • FBS + IUT if MCA-PSV >1.5 MoM
              │              • Planned delivery 34–38 wks
              │
              └─── ICT NEGATIVE (unsensitized)
                        │
                        ▼
              Check partner Rh type
                        │
                        ├─ Partner Rh-NEGATIVE → Fetus must be Rh-negative
                        │                          → No anti-D needed; routine care
                        │
                        └─ Partner Rh-POSITIVE or unknown
                                   │
                                   ▼
                        PROPHYLAXIS PROTOCOL:
                        • Repeat ICT at 20 wks
                        • Anti-D 300 mcg IM at 28 wks (± 34 wks)
                        • Anti-D at ANY sensitizing event within 72 hrs
                        • Post-delivery: check baby's Rh type
                                   │
                                   ├─ Baby Rh-POSITIVE → Anti-D 300 mcg within 72 hrs
                                   │                      ± KB test if large FMH suspected
                                   └─ Baby Rh-NEGATIVE → No anti-D needed

Key Points to Remember

Point	Detail
Window for anti-D	Must be given within 72 hours of sensitizing event (ideally within 24 hrs)
First pregnancy risk	Usually safe — initial IgM response doesn't cross placenta; danger is in subsequent pregnancies
ABO protection	Concurrent ABO incompatibility partially protects the mother (fetal cells cleared by anti-A/B IgM before sensitization occurs)
Rh-negative = homozygous deletion	Rh-negative individuals lack the RHD gene entirely — so no "d" antibody exists
Weak D / partial D	Some women type as Rh-positive but have partial D antigens — may still be at risk; management is institution-specific
Non-D antigens	Anti-Kell (K), anti-c, anti-E can also cause HDFN — detected by ICT; managed similarly to anti-D alloimmunization

Sources:

Robbins, Cotran & Kumar Pathologic Basis of Disease — Immune Hydrops / Etiology & Pathogenesis
Guyton and Hall Textbook of Medical Physiology — Erythroblastosis Fetalis & Prevention
Katzung's Basic and Clinical Pharmacology, 16th Edition — Rh(D) Immune Globulin
Tintinalli's Emergency Medicine — Rh Seroconversion & Anti-D Indications
Emery's Elements of Medical Genetics and Genomics — Rhesus Hemolytic Disease of the Newborn

What is the algorithm of investigation approach for a mother coming with a low SFH for period of gestational age

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Investigation Algorithm for Low Symphysis-Fundal Height (SFH) for Period of Gestation

What Does Low SFH Mean?

SFH (in cm) between 24–36 weeks normally approximates gestational age in weeks (±2 cm). A measurement ≥3–4 cm less than expected for gestational age is the standard trigger for further investigation, raising suspicion of Fetal Growth Restriction (FGR) — a fetus that has not achieved its growth potential.

"Measurement of the symphysis-fundal height is helpful in screening for abnormal fetal growth... but [is] not sensitive enough for accurate detection of most infants with growth restriction." Clinical diagnosis of FGR by physical examination alone is missed almost half the time. — Creasy & Resnik's Maternal-Fetal Medicine

Clinical signs of IUGR include poor increase in fundal height (>4 cm difference from expected) or inadequate maternal weight gain (<100–200 g/week in the third trimester). Diagnosis by clinical means alone is possible in only ~33% of pregnancies. — Pfenninger and Fowler's Procedures for Primary Care

Step 1 — Clinical Assessment at the Visit

Before ordering investigations, take a targeted history and examination to identify the cause of the small fundus.

Confirm Dates First

Question	Significance
Last menstrual period (LMP) — reliable?	Inaccurate dates are the most common explanation for apparent low SFH
First-trimester ultrasound (CRL)?	Crown-rump length before 14 weeks is the most accurate dating method (±5–7 days)
Any previous growth scans as baseline?	Serial measurements by the same observer are more meaningful than single readings

If LMP is unreliable and no first-trimester dating scan was done, any "low SFH" may simply reflect miscalculation of gestational age — this must be excluded before labelling as FGR.

Exclude Non-Pathological Causes

Cause	Feature
Inaccurate dates	No reliable LMP; no early USS
Maternal body habitus (obesity)	SFH notoriously inaccurate in obese patients
Fetal lie (transverse/oblique)	Fundus appears low; on palpation — no pole in pelvis
Engaged head (late 3rd trimester)	Head descends into pelvis → apparent fall in SFH
Empty bladder (slight)	Minimal impact but worth standardising technique

Maternal History for Risk Factors of FGR

Maternal factors:

Hypertension (chronic or gestational / pre-eclampsia)
Diabetes with vasculopathy
Chronic renal insufficiency
Antiphospholipid syndrome / SLE
Smoking, alcohol, cocaine/heroin use
Severe malnutrition / poor weight gain
Prescribed medications (beta-blockers, steroids)
Pregnancy at high altitude

Fetal/placental factors:

Multiple gestation
Chromosomal/structural abnormalities
Congenital infections (rubella, CMV, toxoplasma)
Placental insufficiency / abnormalities

— Creasy & Resnik's Maternal-Fetal Medicine, Box 44.2

Step 2 — First-Line Investigation: Ultrasound

Ultrasound is the single most important investigation. It should be arranged promptly (same-day or within 48 hours depending on urgency).

Biometry — confirm FGR and determine type

Parameter	Role	Notes
Abdominal Circumference (AC)	Best single predictor of FGR — reflects liver glycogen stores / nutritional status	Suspect FGR if AC <15th percentile; >95% sensitivity if AC <2.5th percentile
Estimated Fetal Weight (EFW)	Combines AC, HC, BPD, FL	FGR = EFW or AC <10th percentile (ACOG); more clinically significant <5th or 3rd percentile
Head Circumference (HC)	More shape-independent than BPD	Spared in asymmetric FGR early on
Biparietal Diameter (BPD)	Less useful alone	Falls late in asymmetric FGR; reduced proportionately in symmetric FGR
Femur Length (FL)	Often parallels GA in asymmetric FGR	Most useful in ratios
HC/AC ratio	Distinguishes symmetric from asymmetric	HC/AC ≥0.95; HC/AC >1.0 after 36 wks detects 85% of IUGR
FL/AC ratio	≥23.5% suggests IUGR

Classify FGR Type

Type	Description	Cause
Asymmetric FGR (~80%)	AC/body small; head spared (brain-sparing)	Uteroplacental insufficiency — late onset; hypoxia redistributes blood to brain
Symmetric FGR (~20%)	All measurements proportionately reduced	Early insult — chromosomal, infection, structural; all organs equally affected

Symmetric FGR requires serial scans at 2–3 week intervals if gestational age is uncertain. — Pfenninger and Fowler's Procedures for Primary Care

Amniotic Fluid Volume

Finding	Significance
Oligohydramnios (AFI <5 cm / single deepest pool <2 cm)	Reflects decreased fetal renal perfusion from hypoxia; combined with FGR = high-risk outcome; sensitivity >85% in high-risk populations
Normal fluid	Does not exclude FGR

If oligohydramnios is present with no PROM and no anomalies, FGR is the likely cause. Combination of oligohydramnios + FGR portends a less favourable outcome; delivery at ≥36 weeks generally indicated. — Pfenninger and Fowler's Procedures for Primary Care

Placental Assessment

Finding	Significance
Premature grade III placenta (before 35 weeks)	Further evidence of uteroplacental insufficiency and FGR
Placental mosaicism, infarcts, haematomas	May be primary cause of FGR

Step 3 — Doppler Velocimetry

Once FGR is confirmed on biometry, Doppler studies are essential to assess fetoplacental blood flow and fetal cardiovascular compensation.

Sequence of Doppler Deterioration in FGR

Stage	Doppler Finding	Clinical Significance
Stage 1	↑ Umbilical artery (UA) PI / S:D ratio	Increased placental resistance; early compromise
Stage 2	Absent end-diastolic flow (AEDF) in UA	Severe placental insufficiency
Stage 3	Reversed end-diastolic flow (REDF) in UA	Critical — imminent fetal compromise
Redistribution	↓ MCA PI ("brain-sparing") — MCA/UA ratio (CPR) <1.0	Fetus redistributing blood to brain; brain-sparing response
Late/severe	Absent/reversed a-wave in Ductus Venosus (DV)	Cardiac decompensation; pre-terminal
Late/severe	Pulsations in umbilical vein (UV)	Severe cardiac compromise; imminent death

Sequence of abnormal Doppler parameters in FGR — percentage occurrence before delivery in pregnancies with (grey) vs without (black) preeclampsia

Abnormal Doppler parameters in FGR: UA PI, MCA PI, UA reversed flow (UARF), DV PI, MCA PSV and venous waveforms appear in a predictable sequence. — Creasy & Resnik's Maternal-Fetal Medicine

Step 4 — Fetal Well-being Assessment

Run concurrently with Doppler once FGR is confirmed:

Biophysical Profile (BPP)

Parameter (1 point each)	Normal = 2; Abnormal = 0
Fetal breathing movements (≥1 episode ≥30 sec in 30 min)
Gross body movements (≥3 discrete movements)
Fetal tone (≥1 active extension + return to flexion)
Amniotic fluid volume (AFI ≥5 or deepest pool ≥2 cm)
Non-stress test (NST) (reactive = 2 accelerations in 20 min)

Score	Interpretation
8–10/10	Normal — reassuring
6/10	Equivocal — repeat in 24 hrs or deliver if ≥36 wks
≤4/10	Abnormal — deliver regardless of gestational age

AFV assessment appears to have value as an indicator of fetal outcome. Severe oligohydramnios is associated with a high risk of fetal compromise. In early-onset FGR, AFI <5 cm was present in 89% of pregnancies. — Creasy & Resnik's Maternal-Fetal Medicine

Non-Stress Test (NST) / Cardiotocography (CTG)

Reactive NST: two accelerations of ≥15 bpm × ≥15 sec in 20 minutes
Loss of variability and decelerations are ominous in FGR

Step 5 — Targeted Investigations for Underlying Cause

Once FGR is confirmed, investigate the cause to guide management:

Maternal Investigations

Investigation	Indication / Purpose
Full blood count	Anaemia, thrombocytopenia (pre-eclampsia, HELLP)
Urine dipstick / PCR	Proteinuria → pre-eclampsia
BP measurements	Hypertensive disorders
TORCH serology (if not done)	Rubella, CMV, toxoplasma, HSV — all associated with symmetric FGR
Antiphospholipid antibodies (lupus anticoagulant, anti-cardiolipin, anti-β2-GPI)	Antiphospholipid syndrome — common cause of placental-mediated FGR
Renal function tests	Chronic kidney disease
Uterine artery Doppler	High RI/notching → uteroplacental insufficiency; useful early predictor
Thyroid function	Hypothyroidism → FGR
Random blood glucose / HbA1c	Diabetes with vasculopathy
Drug screen (urine)	Cocaine, heroin use

Fetal Investigations

Investigation	Indication
Detailed anomaly scan	FGR + structural defects → karyotype indicated
Fetal karyotype (amniocentesis or CVS)	FGR diagnosed in 2nd trimester with structural defect; trisomy 13/18/21 all cause FGR
Chromosomal microarray	Standard karyotype + microarray detects 18.8% abnormalities vs 9.3% with karyotype alone in FGR
Viral PCR (amniotic fluid)	If CMV/rubella suspected clinically
Fetal blood sampling (cordocentesis)	Severe FGR — assess pH, PO₂, haematocrit; confirms acidaemia

In FGR diagnosed in the second trimester with a structural defect, karyotype is recommended. Microarray provides a 4% incremental yield for pathogenic copy number variants in isolated FGR with normal karyotype. — Creasy & Resnik's Maternal-Fetal Medicine

Full Investigation Algorithm (Flow Chart)

LOW SFH (≥3–4 cm below expected for GA)
              │
              ▼
STEP 1: CONFIRM DATES
    Reliable LMP + first-trimester CRL?
              │
    ├─── NO/UNCERTAIN ──► Revise EDD using USS biometry
    │                     If dates change → reassess SFH discrepancy
    │
    └─── YES → Proceed
              │
              ▼
STEP 2: EXCLUDE CLINICAL CAUSES
    - Fetal lie (transverse/oblique)?
    - Engaged head (term)?
    - Maternal obesity (SFH unreliable)?
              │
              ▼
STEP 3: ULTRASOUND (urgent)
    ┌─────────────────────────────────────┐
    │ Biometry: AC, EFW, HC, BPD, FL      │
    │ Ratios: HC/AC, FL/AC                │
    │ Amniotic fluid: AFI / deepest pool  │
    │ Placental appearance/grading        │
    │ Fetal anatomy survey               │
    └─────────────────────────────────────┘
              │
    ┌─────────┴────────────┐
    │                      │
EFW/AC ≥10th          EFW/AC <10th percentile
percentile           (FGR confirmed)
    │                      │
Repeat scan          CLASSIFY:
in 2–4 weeks    ┌───────────────────────┐
    │           │ Asymmetric (AC small,  │
    │           │  HC spared) vs        │
    │           │ Symmetric (all small) │
    │           └───────────────────────┘
    │                      │
    │                      ▼
    │           STEP 4: DOPPLER STUDIES
    │           ┌──────────────────────────────────┐
    │           │ Umbilical artery (UA) PI/S:D      │
    │           │ Middle cerebral artery (MCA) PI   │
    │           │ Cerebroplacental ratio (CPR)       │
    │           │ (± DV, UV if UA absent/reversed)  │
    │           └──────────────────────────────────┘
    │                      │
    │           ┌──────────┴──────────────────┐
    │      Normal Doppler            Abnormal Doppler
    │           │                             │
    │      NST/BPP weekly            NST/BPP TWICE WEEKLY
    │      Deliver at 39 wks         + serial Doppler
    │                                         │
    │                              ┌──────────┴──────────┐
    │                         UA AEDF               UA REDF
    │                              │                     │
    │                         Deliver ≥33 wks       DELIVER
    │                         NST/BPP guides         (hospitalize
    │                         if <33 wks             if <30 wks;
    │                                                daily testing)
    │
    └──────► STEP 5: INVESTIGATE CAUSE
             ┌───────────────────────────────────┐
             │ Maternal: BP, urine, FBC, LFTs    │
             │ TORCH serology, aPL antibodies    │
             │ Renal/thyroid/glucose             │
             │ Uterine artery Doppler            │
             │                                   │
             │ Fetal: Detailed anomaly scan       │
             │ Karyotype + microarray if anomaly  │
             │ Viral PCR if infection suspected   │
             └───────────────────────────────────┘

Delivery Timing Summary

Situation	Timing
FGR, normal Doppler, normal BPP/NST	Deliver at 39 weeks
FGR, abnormal UA/MCA, normal BPP/NST	Deliver at 37 weeks
UA AEDF at ≥33 weeks	Deliver
UA AEDF at <33 weeks	Intensive surveillance; DV Doppler guides timing
UA REDF at ≥30 weeks	Deliver
UA REDF at <30 weeks	Hospitalize; daily BPP + Doppler; individualise
Reversed DV a-wave or UV pulsations	Deliver regardless of gestational age if viable
FGR + pre-eclampsia with severe features	Maternal status may dictate earlier delivery

Weekly BPP/NST and UA + MCA Doppler is recommended. Reversed UA end-diastolic flow is an ominous finding — delivery is indicated unless the fetus is extremely premature (<30 weeks). — Creasy & Resnik's Maternal-Fetal Medicine

Antenatal Therapy

Intervention	Evidence
Low-dose aspirin 100–150 mg/day (started before 16 weeks in high-risk women)	Significant reduction in FGR risk (RR 0.56, CI 0.44–0.70) — must start early
Maternal oxygen therapy	Inconclusive evidence; limited use
Vitamins C/E (antioxidants)	Not effective in reducing FGR risk
Delayed cord clamping (≥30–60 sec) at delivery	Associated with decreased odds of mortality/major morbidity in preterm FGR infants
Magnesium sulphate intrapartum	Neuroprotection when delivery <29 weeks

Sources:

Creasy & Resnik's Maternal-Fetal Medicine: Principles and Practice — Chapter 44: Fetal Growth Restriction (Definition, Diagnosis, Doppler, Management)
Pfenninger and Fowler's Procedures for Primary Care — Intrauterine Growth Retardation (Ultrasound Parameters)
Robbins, Cotran & Kumar Pathologic Basis of Disease — Fetal Growth Restriction / Etiology

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