Abdominal pain in pregnancy
Obstetrics
OB triage or the emergency department, any gestation
The first question
What gestation, and is the pain obstetric or not?
Two patients: the gestational age and the maternal stability first, then the fetal status.
- 01
Gestational age
Under 20 weeks: ectopic and miscarriage lead. Over 20: labour, abruption, preeclampsia, and the surgical causes that do not stop for pregnancy.
- 02
Maternal stability and fetal status
Vital signs, then the fetal heart rate and monitoring after viability.
- 03
Obstetric or not
Contractions, bleeding, fluid, hypertension say obstetric. Migration, anorexia, urinary symptoms and biliary pain say otherwise.
- 04
Investigate without delay
Ultrasound first; CT or MRI when the answer matters, because a missed appendicitis harms both patients more than the radiation.
Where it is
Each opens the structure on the 3D pelvis.
History that discriminates
- Site, onset, character, radiation, relation to contractions
- Bleeding, fluid, fetal movements
- Headache, visual symptoms, epigastric pain (preeclampsia)
- Urinary, bowel, biliary symptoms
- Prior surgery, fibroids, ovarian cysts
- Trauma
Examination that discriminates
- Vital signs, temperature
- Uterine tone and tenderness, contractions, fundal height
- Site of maximal tenderness (the appendix migrates upward with the uterus), peritonism, Murphy's sign, renal angle
- Fetal heart rate; monitoring after viability
- Speculum and cervical assessment when labour or rupture is possible and praevia excluded
Investigations
- Urinalysis and culture
- CBC (leucocytosis is physiological), liver enzymes, lipase, urate, creatinine
- Ultrasound: pregnancy, adnexa, appendix, kidneys, gallbladder
- MRI without gadolinium for appendicitis when ultrasound is inconclusive
- Fetal monitoring
The differential
| Diagnosis | Favours | Against | Urgency |
|---|---|---|---|
| Labour (term or preterm) | Regular painful contractions with cervical change | Constant pain without contractions | urgent |
| Abruption | Constant pain, hard tender uterus, bleeding, hypertension | Soft uterus, normal tracing | emergent |
| Preeclampsia with HELLP | Epigastric or right upper quadrant pain with hypertension, headache, abnormal liver enzymes and platelets | Normal blood pressure and bloods | emergent |
| Appendicitis | Migration, anorexia, tenderness displaced upward, fever | Pain tied to contractions | emergent |
| Pyelonephritis | Fever, flank pain, pyuria, rigors | Normal urine | urgent |
| Ovarian torsion or cyst accident | Sudden unilateral pain with vomiting, a known cyst, first or early second trimester | Central pain | emergent |
| Degenerating fibroid | Known fibroid, localised tenderness over it | No fibroid | routine |
| Biliary colic or cholecystitis | Right upper quadrant pain after meals, Murphy's sign, gallstones on scan | Normal gallbladder | urgent |
| Round ligament pain | Sharp, brief, one-sided, with movement, second trimester, everything else normal | Constant pain, any red flag | routine |
Pitfalls this pathway refuses
- Attributing pain to the pregnancy before excluding the causes that kill (appendicitis, abruption, HELLP)
- Withholding imaging out of fear of radiation
- Interpreting a white count of 14 as infection