11.2 Medical & Obstetric Complications of Pregnancy

Medical & Obstetric Complications of Pregnancy

Hypertensive Disorders of Pregnancy

Hypertensive disorders affect 5–10% of pregnancies and represent a leading cause of maternal and perinatal morbidity. Classification is based on gestational age at onset, presence of proteinuria, and organ-specific severe features:

• Chronic Hypertension: Blood pressure ≥140/90 mmHg documented prior to pregnancy or before 20 weeks gestation, persisting >12 weeks postpartum.
• Gestational Hypertension: New-onset BP ≥140/90 mmHg occurring after 20 weeks gestation in the absence of proteinuria or severe features. Resolves <12 weeks postpartum.
• Preeclampsia: New-onset hypertension (≥140/90 mmHg on 2 readings at least 4 hours apart) after 20 weeks gestation accompanied by proteinuria (≥300 mg/24-hour urine collection, urine protein:creatinine ratio ≥0.3, or dipstick 2+).
• Preeclampsia with Severe Features: Diagnosed when preeclampsia is accompanied by ANY of the following severe criteria (proteinuria is NOT required if severe features are present):
  • Severe blood pressure elevation: systolic ≥160 mmHg or diastolic ≥110 mmHg on two occasions at least 15 minutes apart
  • Thrombocytopenia: platelets <100,000/mcL
  • Impaired liver function: transaminases (AST/ALT) ≥2 times upper limit of normal or severe persistent right upper quadrant / epigastric pain
  • Progressive renal insufficiency: serum creatinine >1.1 mg/dL or doubling of baseline serum creatinine
  • Pulmonary edema
  • New-onset cerebral or visual disturbances (persistent severe frontal headache, scotomas, blurred vision)
• Eclampsia: Development of new-onset tonic-clonic seizures in a patient with preeclampsia. Managed with IV magnesium sulfate, blood pressure stabilization, and emergency delivery.
• HELLP Syndrome: A severe variant of preeclampsia defined by Hemolysis (microangiopathic hemolytic anemia with schistocytes, serum total bilirubin >1.2 mg/dL, and LDH >600 U/L), Elevated Liver enzymes (AST/ALT ≥2x upper limit of normal), and Low Platelets (<100,000/mcL). Carries high risk of hepatic subcapsular hematoma rupture, DIC, and placental abruption.

Prevention, Antihypertensives & Seizure Prophylaxis

• Prophylaxis: Low-dose aspirin (81 mg/day) initiated between 12 and 16 weeks gestation for patients at high risk for preeclampsia (prior preeclampsia, multifetal gestation, chronic hypertension, pregestational diabetes, renal disease, autoimmune disease).
• Acute Antihypertensive Therapy: Indicated for severe hypertension (BP ≥160/110 mmHg) to reduce stroke risk. First-line agents include:
  • Intravenous Labetalol: Combined alpha-1 and beta-blocker. Avoid if maternal bradycardia (<60 bpm) or severe asthma.
  • Intravenous Hydralazine: Direct vasodilator. Can cause reflex tachycardia and headache.
  • Oral Immediate-Release Nifedipine: Calcium channel blocker. Preferred if IV access is delayed.
  • Note: ACE inhibitors, ARBs, and direct renin inhibitors are strictly teratogenic (cause renal dysgenesis, oligohydramnios, skull hypoplasia) and contra-indicated in all trimesters.
• Seizure Prophylaxis: Intravenous Magnesium Sulfate (MgSO4) is the agent of choice for seizure prevention in preeclampsia with severe features and for seizure treatment in eclampsia. Administered as a 4–6 g IV loading dose over 15–20 minutes followed by 1–2 g/hour continuous IV maintenance infusion for 24 hours postpartum.
  • Magnesium Toxicity Monitoring: Loss of deep tendon reflexes (patellar reflex) occurs at therapeutic levels of 4–7 mEq/L (loss of DTRs at 8–12 mEq/L; respiratory depression at 12–15 mEq/L; cardiac arrest at >15 mEq/L). Monitor hourly urine output (>30 mL/hr), respiratory rate (>12/min), and patellar reflexes.
  • Antidote for Magnesium Toxicity: Intravenous Calcium Gluconate (1 g IV over 2–5 minutes).
• Timing of Delivery:
  • Preeclampsia without severe features: Delivery at 37 0/7 weeks gestation.
  • Preeclampsia with severe features / HELLP syndrome: Delivery at ≥34 0/7 weeks gestation (or immediately at any gestational age if maternal/fetal condition deteriorates, e.g., eclampsia, DIC, abruption, refractory severe BP).

Gestational Diabetes Mellitus (GDM)

Gestational diabetes arises from human placental lactogen (hPL / human chorionic somatomammotropin) inducing maternal insulin resistance in the 2nd and 3rd trimesters to ensure adequate glucose delivery to the fetus.

• Screening & Diagnosis (2-Step Method at 24-28 weeks):
  • Step 1: 1-hour 50g Glucose Challenge Test (GCT). Serum glucose ≥130–140 mg/dL is positive.
  • Step 2: Diagnostic 3-hour 100g Oral Glucose Tolerance Test (OGTT) following an 8-12 hour fast. GDM is diagnosed if ≥2 values equal or exceed Carpenter-Coustan thresholds:
    • Fasting: ≥95 mg/dL
    • 1-Hour: ≥180 mg/dL
    • 2-Hour: ≥155 mg/dL
    • 3-Hour: ≥140 mg/dL
• Management Protocols:
  • First-line: Nutritional modification (33-40% complex carbohydrates) and light exercise (30 mins post-meal walking).
  • Glycemic Targets: Fasting blood glucose <95 mg/dL, 1-hour postprandial <140 mg/dL, or 2-hour postprandial <120 mg/dL.
  • Pharmacotherapy: If glycemic targets are not achieved after 1–2 weeks of dietary modification, subcutaneous insulin is the first-line pharmacotherapy of choice (does not cross the placenta). Metformin and glyburide are second-line options.
• Fetal & Neonatal Complications: Fetal hyperinsulinemia driven by maternal hyperglycemia leads to fetal macrosomia (EFW >4,500 g), shoulder dystocia, neonatal hypoglycemia (abrupt loss of maternal glucose supply post-delivery while fetal insulin remains high), polycythemia, hyperbilirubinemia, hypocalcemia, and delayed lung maturity (hyaline membrane disease).
• Postpartum Management: Discontinue insulin immediately post-delivery. Perform a 2-hour 75g OGTT at 4–12 weeks postpartum to screen for persistent type 2 diabetes mellitus.

Early Pregnancy Loss & Ectopic Pregnancy

• Ectopic Pregnancy: Implantation outside the endometrial cavity, most commonly in the ampulla of the fallopian tube (95%). Classic presentation: amenorrhea, lower abdominal pain, and vaginal bleeding.
  • Evaluation: Transvaginal ultrasound (TVUS) and quantitative serum beta-hCG. The beta-hCG discriminatory zone (1,500–2,000 mIU/mL) is the level at which an intrauterine gestational sac should reliably be visible on TVUS. An empty uterus with beta-hCG above the discriminatory zone strongly suggests ectopic pregnancy.
  • Medical Management (Methotrexate): Folic acid antagonist that inhibits DNA synthesis in rapidly dividing trophoblastic tissue. Indications for methotrexate:
    1. Hemodynamically stable patient with no severe abdominal pain
    2. Unruptured ectopic mass <3.5 cm in diameter
    3. No fetal cardiac activity on ultrasound
    4. Baseline serum beta-hCG <5,000 mIU/mL
    5. Normal baseline hepatic and renal function, and reliable patient follow-up
  • Surgical Management (Laparoscopic Salpingostomy / Salpingectomy): Indicated for hemodynamically unstable patients, signs of tubal rupture (peritonitis, hemoperitoneum), failed methotrexate therapy, or contraindications to methotrexate.
• Spontaneous Abortion Subtypes: Defined as pregnancy loss prior to 20 weeks gestation.
  • Threatened Abortion: Vaginal bleeding, closed cervical os, fetal cardiac activity present on ultrasound.
  • Inevitable Abortion: Vaginal bleeding, cramping, open cervical os, products of conception visible at os or internal os dilated, no tissue passed yet.
  • Incomplete Abortion: Vaginal bleeding, severe cramping, open cervical os, partial passage of products of conception with retained tissue in uterus.
  • Complete Abortion: Vaginal bleeding/cramping resolved, closed cervical os, complete passage of all products of conception, empty uterine cavity on ultrasound.
  • Missed Abortion: Nonviable fetus retained in utero, closed cervical os, no vaginal bleeding or cramping.

Third-Trimester Hemorrhage & Placental Disorders

Third-trimester vaginal bleeding is an obstetric emergency requiring immediate maternal stabilization and fetal heart rate evaluation.

              [ Suspected Preeclampsia (BP ≥140/90 mmHg after 20 weeks) ]
                                           |
               +---------------------------+---------------------------+
               |                                                       |
  [ Check Proteinuria & Severe Criteria ]                  [ Chronic Hypertension ]
   - Urine Protein ≥300 mg/24h or PCR ≥0.3                   (BP ≥140/90 pre-pregnancy
   - Severe BP ≥160/110 mmHg                                  or <20 weeks gestation)
   - Platelets <100,000/mcL
   - SCr >1.1 mg/dL or ALT/AST ≥2x normal
   - Pulmonary Edema or Cerebral/Visual Symptoms
               |
       +-------+-------+
       |               |
  [ Present ]     [ Absent ] ---> [ Gestational Hypertension ]
       |                               (BP ≥140/90, no proteinuria/severe features)
       v
[ Preeclampsia Confirmed ]
       |
       +-------------------------------+-------------------------------+
       |                                                               |
[ Any Severe Feature Present? ]                                 [ No Severe Features ]
 (BP ≥160/110, Platelets <100k,                                        |
  AST/ALT 2x, SCr >1.1, Headache/Scotomas)                             v
       |                                                [ Delivery at 37 0/7 Weeks ]
       +-------------------------------+
       | Yes                           | Eclampsia (Seizures) / HELLP
       v                               v
[ Preeclampsia with Severe Features ] [ Emergency Stabilization ]
       |
       |- 1. Antihypertensives for BP ≥160/110 (IV Labetalol, IV Hydralazine, Oral Nifedipine)
       |- 2. IV Magnesium Sulfate Loading (4–6 g IV) + Maintenance (1–2 g/hr) for Seizure Prophylaxis
       |- 3. Delivery at ≥34 0/7 Weeks (or immediate delivery if maternal/fetal decompensation)