1.2 Antepartum Obstetric Complications & High-Risk Conditions
Key Takeaways
- Preeclampsia diagnostic criteria require new-onset hypertension (SBP >= 140 or DBP >= 90 mmHg) after 20 weeks gestation plus proteinuria or severe features such as severe persistent headache, thrombocytopenia (< 100,000/uL), or elevated liver enzymes.
- Persistent acute severe hypertension (SBP >= 160 or DBP >= 110 mmHg) requires urgent treatment, generally within 30 to 60 minutes, with IV labetalol, IV hydralazine, or oral immediate-release nifedipine according to the facility algorithm.
- Magnesium sulfate is administered for eclampsia seizure prophylaxis using a 4 to 6 gram IV loading dose followed by a 1 to 2 g/hr infusion; therapeutic serum level is 4.0 to 7.0 mEq/L, and calcium gluconate (1 g IV over 3-5 min) is the antidote for toxicity.
- HELLP syndrome is defined by microangiopathic hemolytic anemia, elevated liver enzymes (AST/ALT >= 2x upper limit of normal), and severe thrombocytopenia (< 100,000/uL), frequently presenting with right upper quadrant or epigastric pain.
- Placenta previa presents with painless, bright red vaginal bleeding and strictly contraindicates digital vaginal examination, whereas placental abruption presents with painful dark vaginal bleeding, uterine hypertonicity, and a rigid, board-like abdomen.
1.2 Antepartum Obstetric Complications & High-Risk Conditions
Antepartum obstetric complications represent acute and chronic threats to maternal-fetal stability. Inpatient obstetric nurses must possess advanced assessment skills to detect subtle clinical deterioration, execute rapid emergency protocols, and administer high-alert medications safely.
Hypertensive Spectrum Disorders & Preeclampsia
Preeclampsia is a multisystem endothelial disorder unique to human pregnancy, characterized by abnormal placental spiral artery remodeling resulting in placental hypoperfusion, systemic vasospasm, capillary leak, and end-organ dysfunction.
Diagnostic Criteria (ACOG Guidelines)
- Gestational Age: At or after 20 weeks gestation in a previously normotensive patient.
- Blood Pressure: Systolic BP >= 140 mmHg or diastolic BP >= 90 mmHg on two occasions at least 4 hours apart.
- Proteinuria:
- >= 300 mg per 24-hour urine collection, OR
- Protein-to-Creatinine ratio >= 0.3, OR
- Urine dipstick 2+ (used only if quantitative methods unavailable).
- Preeclampsia WITHOUT Proteinuria: Diagnosed if new-onset hypertension occurs with any of the following Severe Features:
- Thrombocytopenia: Platelet count < 100,000 /\mu L.
- Renal Insufficiency: Serum creatinine > 1.1 mg/dL (or doubling of baseline).
- Impaired Liver Function: Serum transaminases (AST/ALT) elevated to >= 2 times upper limit of normal, or persistent severe right upper quadrant (RUQ) / epigastric pain.
- Pulmonary Edema: New-onset dyspnea, oxygen desaturation, crackles.
- Neurological Symptoms: Severe persistent headache unresponsive to acetaminophen, or visual scotomata/photopsia.
Preeclampsia with Severe Features Criteria
- Systolic BP >= 160 mmHg or diastolic BP >= 110 mmHg that is persistent and confirmed within a short interval so urgent treatment is not delayed.
- Presence of any of the severe features listed above.
Acute Hypertensive Crisis Management
Severe acute hypertension (SBP >= 160 or DBP >= 110 mmHg) must be treated within 30 to 60 minutes to reduce the risk of maternal hemorrhagic stroke:
- Labetalol IV: Initial 20 mg IV push over 2 minutes. If BP remains above threshold after 10 minutes, administer 40 mg IV, then 80 mg IV after the protocol interval (maximum total cumulative dose 220 mg in the common 20/40/80-mg sequence).
- Hydralazine IV: Initial 5 to 10 mg IV push over 2 minutes. If BP remains elevated after 20 minutes, administer 10 mg IV push.
- Nifedipine (Immediate Release): Initial 10 to 20 mg PO. Repeat in 20 minutes if necessary.
- Treatment goal: Lower persistent severe-range pressure below the emergency threshold while avoiding maternal hypotension; use the current order set and repeated measurements rather than one universal narrow target range.
Eclampsia Seizure Prophylaxis & Magnesium Sulfate Protocol
Magnesium sulfate is the drug of choice for seizure prophylaxis in preeclampsia with severe features and for treatment of eclampsia. A common IV regimen is a 4- to 6-g loading dose followed by 1 to 2 g/hour, but the order set and renal function govern dosing.
Nursing surveillance centers on respiratory rate and oxygenation, level of consciousness, deep-tendon reflexes, urine output, and the independent pump/line check. Routine serum levels are not required in every patient; obtain levels when renal dysfunction, oliguria, toxicity, or the protocol indicates. Loss of reflexes, respiratory depression, increasing somnolence, or oliguria requires stopping the infusion, urgent notification, airway support as needed, and preparation to give calcium gluconate 1 g IV per emergency order. Continue maternal-fetal assessment because magnesium prevents seizures but does not treat severe hypertension.
HELLP Syndrome
HELLP syndrome is a severe variant of preeclampsia occurring in 10% to 20% of preeclamptic pregnancies. It can manifest antepartum (70%) or postpartum (30%).
Diagnostic Laboratory Triad
- H - Hemolysis: Microangiopathic hemolytic anemia. Peripheral blood smear shows schistocytes and burr cells. Serum total bilirubin >= 1.2 mg/dL; Serum Lactate Dehydrogenase (LDH) > 600 IU/L.
- EL - Elevated Liver Enzymes: Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) >= 2 times upper limit of normal (typically AST/ALT > 70 IU/L).
- LP - Low Platelets: Thrombocytopenia with platelet count < 100,000 /\mu L.
Clinical Presentation & Nursing Risk Assessment
- Patients typically present with right upper quadrant (RUQ) or epigastric pain (85%), nausea, vomiting, and malaise. RUQ pain results from hepatic sinusoidal fibrin deposition causing glisson's capsule distension.
- Fatal Complication: Subcapsular hepatic hematoma and liver rupture. Sudden severe RUQ pain radiating to the shoulder accompanied by acute maternal hypotension indicates hepatic rupture, requiring emergency laparotomy and massive transfusion protocol (MTP).
Antepartum Hemorrhage
Antepartum bleeding occurring after 20 weeks gestation demands immediate differential diagnosis between placenta previa, placental abruption, and vasa previa.
Comparison of Antepartum Bleeding Etiologies
| Feature | Placenta Previa | Placental Abruption (Abruptio Placentae) | Vasa Previa |
|---|---|---|---|
| Definition | Placenta implants over or adjacent to internal cervical os | Premature detachment of normally implanted placenta | Fetal vessels course unprotected through membranes over os |
| Bleeding Character | Painless, bright red vaginal bleeding | Painful, dark red vaginal bleeding (or concealed) | Painless, bright red blood upon membrane rupture |
| Uterine Tone | Soft, relaxed, non-tender uterus | Hypertonic, rigid, board-like, tender uterus | Soft, non-tender uterus |
| Fetal Heart Rate | Usually reassuring until maternal shock | Late decelerations, loss of variability, severe bradycardia | Rapid fetal bradycardia / Sinusoidal FHR pattern |
| Digital Exam | ABSOLUTELY CONTRAINDICATED | Contraindicated until previa excluded | Contraindicated |
| Primary Risk Factors | Prior C-section, multiparity, prior curettage, smoking | Maternal hypertension, cocaine use, abdominal trauma, PPROM | In vitro fertilization, succenturiate lobe, velamentous cord |
| Definitive Diagnosis | Transvaginal Ultrasound (TVUS) | Clinical presentation / Retroplacental clot on ultrasound | Color Doppler ultrasound |
Clinical Management Protocols
- Placenta Previa: Complete previa requires scheduled Cesarean delivery at 36 0/7 to 37 6/7 weeks. If active hemorrhage occurs, initiate large-bore IV access (two 16- or 18-gauge catheters), type and crossmatch, continuous EFM, and prepare for emergency C-section.
- Placental Abruption: Complications include Disseminated Intravascular Coagulation (DIC) due to massive release of tissue thromboplastin from the retroplacental clot. Monitor laboratory markers for DIC: Fibrinogen < 200 mg/dL, elevated D-dimer, prolonged PT/PTT, and decreased platelets.
Cervical Insufficiency & Cerclage Management
Cervical insufficiency is the inability of the cervix to retain a pregnancy in the second trimester without labor. It is diagnosed from obstetric history, painless dilation on examination, or selected ultrasound findings in the appropriate risk context. A transvaginal cervical length below 25 mm is a short cervix, not by itself a universal diagnosis of cervical insufficiency.
Management depends on history, gestational age, cervical length, dilation, symptoms, and singleton versus multifetal pregnancy. Vaginal progesterone may be used for a short cervix in selected singleton pregnancies. History-, ultrasound-, or examination-indicated cerclage is not one uniform 12- to 14-week procedure. McDonald and Shirodkar are common techniques. Monitor after placement for contractions, bleeding, membrane rupture, or infection; transvaginal cerclage is generally removed near 36 to 37 weeks or earlier for labor, membrane rupture, or infection according to the obstetric plan.
Hyperemesis Gravidarum
Hyperemesis gravidarum is the severe end of nausea and vomiting in pregnancy. It can produce inability to maintain intake, dehydration, electrolyte or acid-base abnormalities, and weight loss greater than 5% of prepregnancy weight. Persistence beyond a particular gestational week and ketonuria are not required diagnostic criteria. Assess severity, alternative causes, weight trend, vital signs, urine output, electrolytes, renal and liver findings, and nutrition status.
- First-Line Pharmacotherapy: Pyridoxine (Vitamin B6 10-25 mg PO TID) plus Doxylamine (12.5-20 mg PO at bedtime).
- Second-Line Antiemetics: Ondansetron (4-8 mg IV/PO q8h), Promethazine (12.5-25 mg IV/PO/PR q4-6h), or Metoclopramide (5-10 mg IV/PO q6-8h).
- IV Rehydration Nursing Safety Rule: Administer Thiamine (Vitamin B1) 100 mg IV prior to or alongside IV dextrose solutions to prevent Wernicke Encephalopathy in severely malnourished patients.
An inpatient nurse is caring for a patient with preeclampsia with severe features who is receiving a continuous IV infusion of magnesium sulfate at 2 g/hr. Upon assessment, the nurse notes a respiratory rate of 10 breaths/min, absent patellar deep tendon reflexes, and a serum magnesium level of 11.2 mEq/L. Which action should the nurse perform first?
A patient at 30 weeks gestation presents to the triage unit reporting severe right upper quadrant pain, nausea, and visual floaters. Laboratory results reveal: Hemoglobin 9.1 g/dL, Platelets 64,000 /uL, AST 180 IU/L, ALT 195 IU/L, and LDH 780 IU/L. Based on these findings, which condition should the nurse suspect?
A patient at 32 weeks gestation arrives at the labor unit reporting a sudden gush of vaginal blood. Assessment reveals dark red vaginal bleeding, a uterine baseline tone of 28 mmHg with hypertonic contractions, severe abdominal tenderness, and continuous fetal baseline heart rate of 105 bpm with minimal variability. Which diagnosis is most consistent with this clinical picture?