Intrauterine Growth Retardation (IUGR) / Fetal Growth Restriction (FGR)

Source: Creasy & Resnik's Maternal-Fetal Medicine: Principles and Practice; Pfenninger and Fowler's Procedures for Primary Care

Definition

• Small for gestational age (SGA): birth weight < 10th percentile - used as a surrogate for FGR
• Appropriate for gestational age (AGA): 10th to 90th percentile
• Large for gestational age (LGA): > 90th percentile

Incidence

• WHO (1987): approximately 1/4 to 1/3 of all infants weighing < 2500 g at birth have sustained IUGR
• 4-8% of all infants born in developed countries
• 6-30% of infants in developing countries

Classification

Symmetric FGR (20% of FGR cases)

• All fetal measurements (head circumference, abdominal circumference, femur length) fall proportionately
• Suggests an early insult during the phase of cellular hyperplasia (early pregnancy)
• Caused by chromosomal abnormalities, congenital infections, teratogenic drugs
• Head circumference (HC) and femur length (FL) are small along with AC
• Not independently associated with increased perinatal morbidity (compared to AGA infants, when not associated with chromosomal or structural defects)

Asymmetric FGR (minority, but higher-risk group)

• Head and brain are relatively spared ("brain-sparing effect"); abdominal circumference is most affected
• Reflects later-onset placental insufficiency causing redistribution of blood to the brain
• Femur length parallels gestational age from LMP; FL may not be helpful in diagnosis
• Associated with higher risk for intrapartum and neonatal complications

Mixed FGR

• Features of both symmetric and asymmetric patterns

Staging System (Mari Staging)

Etiology and Risk Factors

Maternal Factors

• Pregestational diabetes with vasculopathy
• Chronic hypertensive disease, preeclampsia, gestational hypertension
• Antiphospholipid syndrome
• Chronic renal insufficiency
• Autoimmune disease (e.g., systemic lupus erythematosus)
• Severe nutritional deficiencies
• Pregnancy at high altitude
• Specific medications (e.g., beta blockers)
• Smoking, alcohol use, illicit drug use

Fetal Factors

• Multiple gestation (progressive decrease in fetal weight as number of offspring increases)
• Viral infections (rubella, CMV, varicella, toxoplasmosis, HIV, malaria, Zika virus)
• Aneuploidy: trisomy 13, 18, 21 (in descending order of severity of growth restriction)
• Structural abnormalities - 22.3% frequency of FGR in malformed infants; congenital heart defects and gastroschisis particularly associated
• Chromosomal microarray analysis (used in addition to karyotype) increases detection yield in FGR with structural anomalies by ~4-9%

Placental Factors

• Placental insufficiency / dysfunction (most common cause of asymmetric FGR)
• Placental abnormalities (e.g., circumvallate placenta, bilobed placenta, placenta previa)

Perinatal Mortality and Morbidity

• FGR is associated with increased fetal and neonatal mortality and morbidity at every gestational age
• Risk increases with severity of restriction
• Asymmetric FGR cases have higher risk for intrapartum and neonatal complications
• Combination of oligohydramnios + IUGR portends less favorable outcome
• Long-term consequences include: cerebral palsy (especially in severe or preterm FGR), neurodevelopmental impairment, and increased risk of adult diseases (cardiovascular disease, hypertension, diabetes - Barker/DOHaD hypothesis)

Diagnosis

Clinical Signs

• Poor increase in fundal height (> 4 cm difference from expected fundal height)
• Inadequate maternal weight gain (< 100-200 g/week in the third trimester)
• Clinical diagnosis alone is possible in only ~33% of pregnancies

Ultrasonography (preferred modality)

Oligohydramnios

• Sensitivity for IUGR diagnosis: ~16% in general population
• In high-risk populations: sensitivity can exceed 85%
• If oligohydramnios is present with no PROM or congenital anomalies, IUGR is the likely cause
• Oligohydramnios + IUGR = less favorable outcome; delivery should be considered at ≥ 36 weeks

Doppler Velocimetry

1. Umbilical artery (UA) PI increases - placental resistance rising (Stage 1)
2. Middle cerebral artery (MCA) PI decreases - cerebral vasodilation / brain-sparing (Stage 1)
3. Cerebroplacental ratio (CPR) becomes abnormal - MCA PI / UA PI
4. Absent end-diastolic flow (AEDF) in UA (Stage 2)
5. Reversed end-diastolic flow (REDF) in UA (Stage 3) - ominous
6. Ductus venosus (DV) a-wave abnormality - absent or reversed a-wave indicates impending acidemia / fetal death (Stage 4)
7. Umbilical vein pulsations - late ominous sign

Antenatal Fetal Testing

• Non-stress test (NST): Decreased short-term variability is a late finding in FGR; not a good screening test
• Biophysical profile (BPP): Includes NST + 4 ultrasound parameters (fetal movement, tone, breathing movements, AFV); score 8-10 = reassuring
• Modified BPP (NST + AFV): Acceptable screening tool
• Serial growth scans every 2-3 weeks once FGR is suspected

Management

General Principles

• Identify and treat underlying maternal conditions
• Optimize maternal nutrition
• Smoking cessation
• Low-dose aspirin (started before 16 weeks) in patients with prior FGR or placental insufficiency - can reduce recurrence risk
• Serial Doppler and growth ultrasounds every 2-3 weeks
• Antenatal corticosteroids if preterm delivery anticipated (< 34 weeks)

Delivery Timing Guidelines (> 30 weeks)

• Delivery should not be delayed beyond 39 weeks in any FGR - risk of fetal demise rises significantly at term
• At ≥ 36 weeks with oligohydramnios + IUGR, risk of intrauterine loss may mandate delivery

Route of Delivery

• No proven advantage of elective cesarean over vaginal delivery in FGR (even preterm)
• An unfavorable cervix is not a reason to avoid induction
• For cervical ripening: mechanical methods (balloon catheter) preferred over prostaglandins in FGR; if Bishop score > 6, oxytocin is used
• In premature FGR with reversed UA flow and unfavorable cervix: option of scheduled cesarean is reasonable (many of these fetuses will not tolerate labor)
• Magnesium sulfate intrapartum if delivery < 29 weeks (reduces neurodevelopmental impairment)
• Continuous intrapartum fetal monitoring is essential

Long-Term Outcomes

• Increased risk of cerebral palsy (especially in those with associated preterm birth or severe FGR)
• Neurodevelopmental and cognitive impairment (reduced verbal IQ scores)
• Barker hypothesis / Developmental Origins of Health and Disease (DOHaD): IUGR infants are at higher lifetime risk for hypertension, cardiovascular disease, and type 2 diabetes

• Creasy & Resnik's Maternal-Fetal Medicine: Principles and Practice, Chapter 44
• Pfenninger and Fowler's Procedures for Primary Care, 3rd Ed.

Forceps Delivery

Sources: Creasy & Resnik's Maternal-Fetal Medicine; Pfenninger & Fowler's Procedures for Primary Care; Textbook of Family Medicine 9e

Introduction and History

Simpson forceps - the most commonly used instrument for outlet and low forceps delivery

Anatomy of the Forceps

• Handle
• Shank
• Blade (with a cephalic curve to fit the fetal head and a pelvic curve to follow the birth canal)

Classification (ACOG 1988/1991 Criteria)

Prerequisites (ABCDEFGHIJ Mnemonic - ALSO Curriculum)

• Fetal head must be engaged
• Head position must be known
• Membranes must be ruptured
• No cephalopelvic disproportion
• Adequate maternal pelvis

Indications

• Arrest of labor in the second stage
• Maternal exhaustion
• Inability to push effectively
• Medical conditions requiring shortened second stage (cardiac disease, cerebrovascular disease, severe hypertension)

• Non-reassuring fetal heart rate pattern (fetal distress) in the second stage
• Prolapsed cord with imminent delivery

Contraindications

• Unengaged fetal head (absolute)
• Cervix not fully dilated
• Unknown fetal head position
• Fetal demineralization disorders (osteogenesis imperfecta)
• Fetal coagulopathy (e.g., known hemophilia)
• Malpresentations (face presentation with mentum posterior; brow presentation)
• Cephalopelvic disproportion

Technique (Occiput Anterior - OA Delivery)

1. Articulate the forceps to ensure proper fit, then disarticulate.
2. Take the left handle in the left hand, holding it like a pencil with the concave cephalic curve toward the vulva, shank directed upward perpendicular to the floor.
3. Ease the left blade along the left side of the fetal head, using the right hand inside to protect the maternal sidewall and guide the blade into position.
4. Insert the right blade symmetrically on the right side, using the left hand to guide.
5. If correctly applied, the handles should fit together and lock easily.

• Posterior fontanelle should be midway between the shanks (about 1 fingerbreadth above the interlocked shanks)
• Sagittal suture should be midline and midway between the shanks (perpendicular to the shanks)
• Fenestration should barely admit a fingertip between blade and fetal head

• The pelvic curve is a J-shaped curve from inlet to outlet
• One hand pulls the handles in the direction they extend (horizontal vector, outward)
• The other hand on the shaft pushes downward
• These two vectors sum to an outward-and-downward force initially
• As the crown moves under the symphysis, traction direction shifts upward
• Traction is applied with contractions and maternal pushing; released between contractions

• Rotate head if needed to OA (done during uterine relaxation, just before a contraction; mild flexion aids rotation)
• When the jaw is reachable, remove the forceps - in the reverse order and direction of placement
• Assess the need for episiotomy based on perineal distention; removing forceps before head delivery may actually avoid the need for episiotomy
• Inspect vagina and cervix carefully for lacerations after delivery

Outlet forceps delivery: traction is first directed downward so the fetal head clears the pubic symphysis, then upward to deliver in extension.

• Blades should be equidistant from the midline of the face and brow (not posterior fontanelle)
• Horizontal traction continues until the base of the infant's nose passes under the symphysis
• Greater perineal distention expected; a larger episiotomy may be needed

Complications

Maternal Complications

• Perineal, vaginal, and cervical lacerations (3rd and 4th degree tears)
• Bladder and urethral injury
• Urinary retention (identified as a risk factor in a 2024 meta-analysis, PMID 38970657)
• Postpartum hemorrhage
• Pelvic floor injury / long-term pelvic organ prolapse and incontinence
• Maternal injury is generally more frequent and more severe with forceps than with vacuum extraction

Neonatal Complications

• Facial nerve palsy (pressure on facial nerve from blades)
• Cephalohematoma (subperiosteal blood collection)
• Skull fracture (rare)
• Intracranial hemorrhage - a large California study (n=583,340) found no statistically significant difference in intracranial hemorrhage between vacuum, forceps, and cesarean delivery when fetal distress required operative delivery; however, combined use of both vacuum and forceps resulted in a rate of intracranial hemorrhage 7.4 times greater than spontaneous delivery and 3.4 times greater than vacuum alone
• Eye injuries (corneal abrasions, retinal hemorrhage - less common than with vacuum)
• Brachial plexus injury (rare)
• Sequential instrument use (vacuum then forceps) significantly increases both maternal and neonatal injury and should be avoided

Long-Term Neonatal Outcomes

• Multiple large studies found no significant difference in IQ or long-term neurodevelopmental outcomes between forceps delivery and spontaneous or cesarean delivery when modern criteria (post-1991 ACOG) are applied
• The earlier studies suggesting lower IQ scores with mid-forceps used older (1965) classification criteria - when reclassified by modern criteria, mid-forceps cases in those studies had significantly worse immediate outcomes

Forceps vs. Vacuum Extractor

Mid-Forceps Delivery - Special Considerations

• Should be undertaken with caution
• Requires willingness to abandon the procedure and proceed to cesarean delivery if:
  • Difficulty with proper application
  • Head does not easily descend or rotate
• Use and teaching of mid-forceps under appropriate circumstances by adequately trained individuals is in accord with current ACOG recommendations

Advantages of Forceps Delivery

Advantages Over Vacuum Extraction

Advantages Over Cesarean Section

General Advantages of Operative Vaginal Delivery (Forceps/Vacuum) as a Category

• Shortens the second stage of labor - beneficial when maternal pushing is ineffective (exhaustion, regional anesthesia, cardiac/cerebrovascular disease)
• Provides a controlled delivery with protection of the perineum compared to unassisted precipitous delivery
• Can be performed under regional anesthesia already in place, avoiding need for general anesthesia

Summary: When Forceps Are Specifically Preferred Over Vacuum

1. Face presentation (mentum anterior) - vacuum cannot be applied to the face
2. Preterm fetus (< 34 weeks) - forceps protect the soft skull better than vacuum suction
3. Aftercoming head in breech delivery
4. Need for active rotation > 45° (Kjelland's forceps)
5. When the operator is more skilled with forceps than vacuum
6. When rapid delivery is required and vacuum failure is not an option

Modes of Termination of Ectopic Pregnancy

Sources: Rosen's Emergency Medicine; Berek & Novak's Gynecology; Tintinalli's Emergency Medicine; Bailey & Love's Surgery

Overview

Natural (Spontaneous) Modes of Termination

1. Tubal Rupture

• As the trophoblast grows, it erodes through the tubal wall, causing rupture
• Leads to massive intraperitoneal hemorrhage - a surgical emergency
• Can occur with or without prior symptoms
• Cornual (interstitial) pregnancy is especially dangerous because the growing embryo can use the myometrial blood supply to grow larger (10-14 weeks) before rupture, causing catastrophic hemorrhage
• Important: Tubal rupture can occur even when β-hCG levels are falling
• Clinically: sudden severe abdominal pain, peritoneal signs, shoulder tip pain (diaphragmatic irritation from blood), haemodynamic collapse
• Site of rupture determines timing:
  • Isthmic ectopic: ruptures early (~6 weeks) - narrow lumen
  • Ampullary ectopic: ruptures later (~8 weeks) - wider, more distensible
  • Interstitial/cornual ectopic: ruptures latest (~12-14 weeks) - surrounded by myometrium

2. Tubal Abortion

• The conceptus is extruded through the fimbriated end of the fallopian tube into the peritoneal cavity
• The trophoblast separates from the tubal wall; the embryo is expelled
• Blood leaks intermittently through the tubal wall or out of the fimbrial ends, with spillage into the peritoneal cavity
• Bleeding and symptoms are typically intermittent, unlike the sudden onset of rupture
• The extruded products may:
  • Be reabsorbed spontaneously (common with small products)
  • Re-implant in the peritoneal cavity as a secondary abdominal pregnancy (rare)
• Clinically: intermittent crampy pain, light-to-moderate vaginal bleeding, less acute than rupture

3. Spontaneous Resolution / Resorption (Involution)

• Some ectopic pregnancies simply die and are resorbed without rupture or abortion
• The trophoblast stops growing, β-hCG levels fall, and the pregnancy resolves spontaneously
• Most likely when:
  • Initial β-hCG is very low (< 200 mIU/mL - reported 88% success rate of spontaneous remission)
  • β-hCG ratio at 48 hours vs. initial level is < 0.87 (predicts a failing pregnancy of unknown location)
• Caution: Tubal rupture can still occur even as β-hCG falls - these patients must be followed with serial β-hCG until levels are undetectable

Summary Table: Natural Modes

Rare/Historical Natural Outcomes

Active (Treatment) Modes of Termination

1. Expectant Management

• For hemodynamically stable patients with very low and falling β-hCG (< 200 mIU/mL)
• Serial β-hCG monitoring until undetectable
• Risk of rupture persists even with falling levels - requires close follow-up

2. Medical Management - Methotrexate (MTX)

• Mechanism: Folate antagonist - kills rapidly dividing trophoblastic cells
• Single-dose protocol: MTX 50 mg/m² IM; β-hCG measured on days 4 and 7; if < 15% fall, repeat dose
• Multi-dose protocol: MTX on days 1, 3, 5, 7 alternating with folinic acid rescue
• Criteria for MTX (must meet ALL):
  • Hemodynamically stable
  • No signs of rupture
  • β-hCG < 5000 mIU/mL (some guidelines allow up to 10,000)
  • No fetal cardiac activity on ultrasound
  • No contraindications (renal/hepatic disease, immunodeficiency, blood dyscrasias)
• "Separation pain" at days 3-7 is common (tubal distension from therapeutic tubal abortion/haematoma) - must distinguish from rupture pain
• A 2024 meta-analysis found letrozole alone or combined with MTX (PMID 39384737) may offer an alternative medical approach

3. Surgical Management

• Linear incision over the ectopic; products removed; tube left open to heal by secondary intention
• Preserves the fallopian tube - preferred when contralateral tube is absent or damaged
• Risk of persistent trophoblast (4-15%) - requires post-op β-hCG monitoring; treated with MTX if needed
• Higher persistent ectopic rate with laparoscopic vs. open salpingostomy

• Removal of the entire affected fallopian tube
• Preferred when: tube is severely damaged, rupture has occurred, haemostasis is difficult, or patient has completed childbearing
• Lower risk of persistent trophoblast; lower recurrence risk in that tube

• Laparoscopic (preferred when patient is stable): less blood loss, faster recovery, shorter hospital stay
• Laparotomy: for haemodynamically unstable/ruptured cases or failed laparoscopy

4. Special Cases

• Cervical ectopic: Methotrexate (systemic or local injection) is first-line; surgical intervention risks catastrophic haemorrhage
• Cornual/interstitial ectopic: Medical (MTX) preferred if diagnosed early; wedge resection or laparoscopic cornuectomy if surgery needed
• Abdominal (secondary) pregnancy: Laparotomy; placenta may be left in situ if removal risks haemorrhage
• Persistent trophoblastic tissue after salpingostomy: MTX is treatment of choice (tissue may not be confined to tube and may not be identifiable at re-operation)