›Maximum 3 g in 24 hours if body weight is below 50 kg or there is hepatic impairment
›First-line and safe throughout pregnancy
›Schedule it rather than give it as required for ongoing pain
›Opioids
›Oxycodone 5 mg PO every 4 to 6 hours as required for moderate pain
›Morphine 2.5 to 5 mg IV every 2 to 4 hours titrated for severe pain
›Co-prescribe a stimulant laxative (senna 15 mg PO at night) and a stool softener (docusate 100 mg PO twice daily)
›Opioid-induced constipation worsens distension and can mask abdominal compartment syndrome
›Short courses are acceptable in pregnancy; avoid sustained use near term because of neonatal withdrawal
›Non-steroidal anti-inflammatory drugs
›Ibuprofen 400 mg PO every 6 to 8 hours or naproxen 500 mg PO twice daily is the usual trial dose but is contraindicated in OHSS
›Reduces renal perfusion in an already prerenal state and inhibits platelets before procedures
›After 20 weeks gestation it causes fetal ductal constriction and oligohydramnios, and it is avoided earlier for implantation concerns
›The caution applies to topical and over-the-counter non-steroidal drugs the patient may take at home
›Antiemetics
›Cyclizine 50 mg PO or IV every 8 hours
›Metoclopramide 10 mg PO or IV every 8 hours
›Maximum 30 mg in 24 hours and maximum 5 days because of extrapyramidal effects
›Acceptable in pregnancy
›Ondansetron 4 mg PO or IV every 8 hours as required
›Maximum 16 mg in 24 hours by the IV route; check QT, potassium and magnesium if repeated
›In the first trimester discuss the small absolute increase in orofacial cleft risk and reserve it for when first-line agents fail
›Doxylamine 10 mg with pyridoxine 10 mg, two tablets at night up to four tablets daily, is a pregnancy first-line option
Thromboprophylaxis and established venous thromboembolism
›Universal thromboprophylaxis for admitted patients
›Enoxaparin 40 mg SC once daily (dalteparin 5000 units SC once daily, tinzaparin 4500 units SC once daily)
›Weight-adjusted dosing (enoxaparin 0.5 mg/kg SC once daily) if body weight is above 90 to 100 kg
›Renal impairment with creatinine clearance below 30 ml/min: enoxaparin 20 mg SC once daily, or unfractionated heparin 5000 units SC every 12 hours
›Consider anti-Xa monitoring at extremes of weight, in renal impairment and in pregnancy
›Add graduated compression stockings and encourage early mobilisation and hydration
›Continue prophylaxis until OHSS has resolved
›If pregnancy continues, continue for at least the first trimester, and longer with additional risk factors, per obstetric haematology advice
›Withholding prophylaxis
›Only with active haemorrhage such as ruptured-cyst haemoperitoneum or intra-abdominal bleeding
›Reassess every 12 to 24 hours and start as soon as bleeding is controlled
›Treatment-dose anticoagulation for confirmed thromboembolism
›Enoxaparin 1 mg/kg SC every 12 hours, with twice-daily dosing preferred in pregnancy
›Anti-Xa monitoring in pregnancy, renal impairment and extremes of weight
›Avoid direct oral anticoagulants and warfarin in pregnancy (teratogenicity, fetal bleeding, placental transfer)
›Unfractionated heparin 80 units/kg IV bolus then 18 units/kg/h infusion titrated to anti-Xa or activated partial thromboplastin time
›Preferred when delivery, surgery or paracentesis is imminent, or in severe renal failure
›Check activated partial thromboplastin time or anti-Xa every 6 hours until therapeutic, then daily
›Duration at least 3 months, and throughout pregnancy plus 6 weeks postpartum if pregnant
›Systemic thrombolysis
›Reserve it for massive pulmonary embolism with haemodynamic collapse
›Bleeding risk is high from recent oocyte-retrieval punctures and engorged ovaries; prefer catheter-directed therapy or surgical embolectomy
Paracentesis and drainage of effusions
›Indications for paracentesis
›Tense ascites causing pain, respiratory compromise or oliguria
›Rising creatinine or falling urine output attributable to raised intra-abdominal pressure
›Abdominal compartment syndrome with bladder pressure above 20 mmHg and new organ dysfunction
›Technique
›Ultrasound-guided transabdominal or transvaginal drainage, avoiding the enlarged ovaries and inferior epigastric vessels
›Drain to symptom relief; large-volume drainage of several litres is often needed and may be repeated
›An indwelling pigtail catheter reduces repeated punctures when reaccumulation is rapid
›Do not autotransfuse ascitic fluid
›Fluid replacement with drainage
›Give human albumin 20 percent about 100 ml (20 g) for every 2 to 3 litres of ascites removed to limit post-drainage circulatory dysfunction
›Monitor blood pressure and haematocrit during and after drainage
›Pleural effusion
›Most effusions resolve with ascites drainage and supportive care
›Reserve thoracocentesis for a large effusion causing refractory hypoxia or distress
›Correct coagulation and time it around low molecular weight heparin dosing
Dopamine agonists and adjuncts
›Cabergoline
›Cabergoline 0.5 mg PO once daily for 8 days
›Reduces VEGF-receptor phosphorylation and capillary permeability without affecting pregnancy rates
›Most effective for prevention at the time of trigger; benefit in established early OHSS is modest
›Expect nausea and postural hypotension; take it with food at night
›Alternatives: quinagolide 50 to 100 mcg PO once daily, or bromocriptine 2.5 mg PO twice daily (or 2.5 mg per rectum if vomiting)
›Avoid it with uncontrolled hypertension, since dopamine agonists can cause vasospasm
›Luteal support and the trigger
›Use vaginal progesterone (for example 400 mg twice daily) for luteal support, never hCG, in a patient at risk of or with OHSS
›Give no further hCG; a freeze-all strategy removes the pregnancy-hCG driver of late OHSS
›Antibiotics
›Not indicated routinely; the leukocytosis of OHSS is not infection
›Treat a documented or strongly suspected infection: for pelvic sepsis, piperacillin-tazobactam 4.5 g IV every 8 hours, or ceftriaxone 2 g IV once daily plus metronidazole 500 mg IV every 8 hours
›Interventions that are not indicated
›Tranexamic acid, which is prothrombotic in an already hypercoagulable state
›Renal-dose dopamine and routine corticosteroids
Management of ovarian torsion and haemorrhage
›Ovarian torsion
›Suspect it with sudden severe unilateral pain, vomiting and adnexal tenderness; Doppler flow may be preserved
›Urgent gynaecology referral for laparoscopy; do not delay surgery for imaging when suspicion is high
›Detorsion and ovarian conservation are preferred; avoid oophorectomy in a stimulated ovary
›Even a dusky ovary usually recovers after detorsion
›Cyst rupture and haemoperitoneum
›Suspect it with acute pain, free fluid and a falling haematocrit
›Resuscitate with crystalloid and blood products, correct coagulopathy and hold anticoagulation
›Many settle with observation; operate for haemodynamic instability or ongoing bleeding
›Handle enlarged ovaries minimally, since they are friable and bleed readily
›Concurrent ectopic or heterotopic pregnancy
›Maintain suspicion despite a confirmed intrauterine pregnancy
›Involve gynaecology for surgical management that preserves the intrauterine pregnancy where possible
Critical care complications
›Acute respiratory distress syndrome
›Lung-protective ventilation with tidal volume 6 ml/kg predicted body weight and plateau pressure below 30 cmH2O
›Drain tense ascites to improve chest wall compliance and lower the pressure needed
›Careful fluid balance, since the capillary leak makes the lungs vulnerable to any excess
›Consider prone positioning for refractory hypoxia if the abdomen is decompressed and the pregnancy allows
›Acute kidney injury
›Optimise intravascular volume with crystalloid then albumin, and relieve raised intra-abdominal pressure by paracentesis
›Start renal replacement therapy for refractory hyperkalaemia, acidosis, or fluid overload with anuria
›Most OHSS-related acute kidney injury is reversible as the capillary leak resolves
›Abdominal compartment syndrome
›Measure bladder pressure serially when the abdomen is tense
›A sustained pressure above 20 mmHg with new organ dysfunction warrants therapeutic paracentesis
›Analgesia, sedation and nasogastric decompression lower intra-abdominal pressure adjunctively
›Paracentesis is the definitive decompression; laparotomy is almost never appropriate here
›Therapy-is-not-working troubleshooting
›Persistent oliguria despite crystalloid and albumin: measure intra-abdominal pressure and drain if it is raised; if it is normal and oliguria persists, escalate to critical care and consider renal replacement
›Rising haematocrit despite fluids: increase albumin, exclude ongoing haemorrhage and escalate paracentesis
›Worsening dyspnoea after ascites drainage: image for pulmonary embolism, echo for pericardial effusion and consider ARDS
›Escalating pain despite analgesia: re-image for torsion, cyst rupture or haemoperitoneum