Acute pelvic pain

Acute pelvic pain is pain in the lower abdomen or pelvis lasting under 3 months, usually of sudden or recent onset. In a woman of reproductive age, ectopic pregnancy must be excluded first. The main clinical point is to separate life threatening conditions needing the same day action (ectopic pregnancy, ovarian torsion, tubo ovarian abscess, appendicitis, haemorrhage, sepsis) from self limited and benign causes using pregnancy testing, examination and early ultrasound.

Clinical relevance. Missed ectopic pregnancy remains a leading cause of maternal death in the first trimester. Delay in diagnosing torsion reduces ovarian salvage, and delay in treating pelvic infection causes tubal damage.

Anatomy. Pain arises from the uterus, adnexa, bladder, ureters, appendix, terminal ileum, sigmoid colon, rectum, peritoneum, pelvic vessels, pelvic floor and abdominal wall. Visceral pain is poorly localised and midline, and parietal peritoneal pain is sharp and localised.

Classification. By pregnancy status: pregnancy related (ectopic, miscarriage, pregnancy of unknown location, and late pregnancy causes) or non pregnant. By cause: gynaecological, urological, gastrointestinal, vascular and other. By urgency: life threatening, urgent surgical, and benign. Temporal patterns. Sudden severe unilateral pain with vomiting suggests torsion. Sudden pain after intercourse or exercise suggests cyst rupture.

Gradual central pain moving to the right iliac fossa suggests appendicitis. Pain with fever and discharge suggests pelvic inflammatory disease. Colicky flank pain radiating to the groin suggests ureteric stone.

History

• Pain: onset (sudden or gradual), site, radiation (shoulder tip pain with diaphragmatic irritation from haemoperitoneum), character, severity from 0 to 10, relation to menses, intercourse, movement, urine and bowel.
• Pregnancy: last menstrual period, contraception, possibility of pregnancy, previous ectopic pregnancy, tubal surgery, fertility treatment, pelvic inflammatory disease, intrauterine device, smoking.
• Bleeding and discharge: vaginal bleeding (amount, clots, passage of tissue), discharge, dyspareunia.
• Associated: fever, rigors, nausea and vomiting, anorexia, diarrhoea, constipation, dysuria, haematuria, syncope or presyncope.
• Gynaecological history: endometriosis, ovarian cysts, fibroids, ovulation induction (ovarian hyperstimulation), previous surgery.
• Infection risk: new partners, symptoms in partner, previous sexually transmitted infection.
• Drugs: anticoagulants, hormonal treatment, recent antibiotics.
• Assault or abuse, and any history in a girl or adolescent.

Examination

• Vital signs: pulse over 100 beats/min, systolic blood pressure under 100 mmHg, shock index (pulse divided by systolic pressure) over 0.9, temperature, respiratory rate, oxygen saturation, capillary refill.
• Pallor and abdominal examination: distension, guarding, rebound, tenderness site, mass, hernia, McBurney point and Rovsing sign (appendicitis), loin tenderness.
• Speculum: bleeding, discharge, cervical os dilatation or products in the os, cervical lesion, intrauterine device threads.
• Bimanual: cervical motion tenderness, uterine size and tenderness, adnexal mass or tenderness, pouch of Douglas fullness or tenderness.
• Rectal examination when appendicitis or pelvic abscess is possible.
• Point of care ultrasound: free fluid in the pouch of Douglas or Morison pouch, intrauterine pregnancy.

Red flags

• Haemodynamic instability, shoulder tip pain or syncope with a positive pregnancy test (ruptured ectopic pregnancy).
• Peritonism or rigid abdomen.
• Sudden severe unilateral pain with vomiting (torsion).
• Fever with cervical motion tenderness, rigors or adnexal mass (pelvic inflammatory disease, tubo ovarian abscess, sepsis).
• Pregnancy with severe pain and bleeding, hypertension, or reduced foetal movements (abruption, uterine rupture).
• Pain after recent intrauterine procedure, delivery or device insertion (perforation, retained products, sepsis).
• Pregnancy of unknown location with pain.
• Pain in a girl with delayed menarche or cyclical pain with a pelvic mass.

Special groups

• Pregnancy: first trimester pain needs ultrasound for site. Later pregnancy: abruption, uterine rupture, labour, pre eclampsia, appendicitis, ligament pain, and pyelonephritis.
• Girls and adolescents: torsion, appendicitis, haematocolpos, and pelvic inflammatory disease; avoid unnecessary internal examination.
• Postmenopausal women: appendicitis, diverticulitis, malignancy with torsion or bleeding, and bowel obstruction.

Organised by system, with the pregnancy related causes first. Each cause is common unless marked serious or uncommon.

Pregnancy related

• Serious: ectopic pregnancy (tubal, cervical, caesarean scar, interstitial, abdominal) and heterotopic pregnancy.
• Miscarriage: threatened, inevitable, incomplete, missed and septic.
• Pregnancy of unknown location.
• Gestational trophoblastic disease with theca lutein cysts.
• Serious (later pregnancy): placental abruption, uterine rupture, preterm labour, chorioamnionitis, pre eclampsia with HELLP syndrome.
• Ovarian hyperstimulation syndrome after ovulation induction.
• Corpus luteum rupture or haemorrhage.
• Round ligament pain, symphysis pubis dysfunction.

Gynaecological, non pregnant

• Dysmenorrhoea and ovulation pain (mittelschmerz).
• Ruptured or haemorrhagic ovarian cyst, endometrioma rupture.
• Pelvic inflammatory disease and endometritis.
• Serious: tubo ovarian abscess.
• Serious: ovarian torsion (including adnexal torsion with a cyst or mass, and torsion of a normal ovary in girls).
• Degeneration, torsion or prolapse of a fibroid.
• Endometriosis flare.
• Haematometra, haematocolpos, and obstructed uterine anomalies.
• Retained or migrated intrauterine device, uterine perforation.
• Ovarian tumour with haemorrhage, torsion or rupture (benign or malignant).
• Hydrosalpinx intermittent pain.
• Uterine inversion (postpartum).

Urological

• Urinary tract infection, cystitis, pyelonephritis.
• Ureteric colic from stone.
• Urinary retention and bladder distension.
• Urethral diverticulum and caruncle.

Gastrointestinal

• Serious: appendicitis.
• Diverticulitis, inflammatory bowel disease flare, infectious enteritis, mesenteric adenitis (children).
• Constipation and faecal impaction.
• Bowel obstruction and perforation (serious), incarcerated hernia.
• Irritable bowel syndrome flare.
• Serious: colorectal cancer with obstruction or perforation.

Vascular and other

• Serious: ruptured aneurysm of an iliac or uterine artery, aortic dissection, ovarian vein thrombosis (postpartum), mesenteric ischaemia.
• Abdominal wall pain, rectus sheath haematoma (anticoagulated), herpes zoster before the rash.
• Pelvic congestion syndrome, musculoskeletal pain.
• Diabetic ketoacidosis, sickle cell crisis, porphyria, and abdominal migraine (children).
• Sexual assault trauma.

Stepwise reasoning

1. Resuscitate when unstable and obtain intravenous access.
2. Perform a pregnancy test in every woman of reproductive age; if positive, assess for ectopic pregnancy by ultrasound and quantitative beta hCG.
3. If negative, examine for peritonism, infection and adnexal pathology, then image with ultrasound.
4. Use CT or MRI for non gynaecological causes when ultrasound does not explain pain, and proceed to laparoscopy for suspected torsion or abscess without delay.
5. Reassess at intervals, because findings evolve.

Immediate tests

• Urine pregnancy test (sensitivity high from about 3 to 4 weeks of gestation); serum quantitative beta hCG when positive.
• Full blood count, group and save, and crossmatch when bleeding or surgery is likely; rhesus status.
• C reactive protein, urea, creatinine, electrolytes, liver function tests, glucose, lactate, and blood cultures when septic.
• Urinalysis and midstream urine culture; vaginal and cervical swabs and nucleic acid amplification tests for chlamydia, gonorrhoea, Trichomonas vaginalis and Mycoplasma genitalium.
• Coagulation screen when bleeding or in anticoagulated women.
• Lipase when upper abdominal pain, and a venous blood gas or ketones when diabetic.

Imaging

• Transvaginal ultrasound, supplemented by transabdominal ultrasound, is first line. Ectopic pregnancy: no intrauterine pregnancy with an adnexal mass (ring sign), complex or free fluid (echogenic fluid or fluid in Morison pouch indicates significant haemoperitoneum). Ovarian torsion: enlarged ovary (over 4 cm, often with a mass), peripheral follicles, whirlpool sign of the pedicle, free fluid; normal arterial or venous Doppler flow does not exclude torsion. Pelvic inflammatory disease: thick fluid filled tubes, cogwheel sign, complex adnexal mass, free fluid. Appendicitis: non compressible blind ending tube over 6 mm.
• Beta hCG discriminatory level: an intrauterine gestational sac is usually visible on transvaginal ultrasound once beta hCG exceeds about 1500 to 3500 IU/L; absence of a sac over this level suggests ectopic or failing pregnancy. In pregnancy of unknown location, repeat beta hCG at 48 hours: a rise of less than about 49 to 63% (depends on starting level) or a fall of less than 50% suggests an abnormal pregnancy and needs review; a fall over 50% in 48 hours with a low starting level supports a failing pregnancy.
• CT abdomen and pelvis with intravenous contrast for suspected appendicitis, diverticulitis, obstruction, abscess or perforation in non pregnant women, and non contrast low dose CT for ureteric stone. MRI in pregnancy for suspected appendicitis when ultrasound is inconclusive.
• Doppler ultrasound or CT venography for ovarian vein thrombosis.

Procedures

• Diagnostic laparoscopy for suspected torsion, ruptured ectopic pregnancy with instability, tubo ovarian abscess not responding to treatment, and unexplained peritonism.
• Culdocentesis is not used.

Limitations. Ultrasound has limited sensitivity for early ectopic pregnancy (about 90 to 95% for transvaginal ultrasound in experienced hands) and a normal Doppler does not exclude torsion. Urine pregnancy tests can be falsely negative at very early gestation. Pain does not match the extent of disease, and ectopic pregnancy occurs with an intrauterine device in place. Appendicitis in pregnancy can present with atypical site.

Immediate steps. Check airway, breathing and circulation. Give oxygen if saturation is under 94%.

Insert two large bore intravenous cannulae, send blood for group and crossmatch, full blood count and beta hCG, and give crystalloid in aliquots of 250 to 500 mL, aiming for a systolic pressure of about 90 to 100 mmHg until haemorrhage is controlled. Activate the major haemorrhage process for haemorrhagic shock (transfuse blood early and give tranexamic acid 1 g intravenously over 10 minutes within 3 hours of onset for ongoing haemorrhage).

Call the gynaecology and anaesthetic teams. Keep the patient nil by mouth when surgery is possible. Give anti D immunoglobulin 250 IU intramuscularly within 72 hours to rhesus negative women with ectopic pregnancy or surgical management of miscarriage.

Analgesia and symptom control

• Paracetamol 1 g intravenously or orally every 6 hours, maximum 4 g daily (3 g daily in hepatic impairment, malnutrition or under 50 kg with 15 mg/kg each dose).
• Morphine 2 to 5 mg intravenously every 5 to 10 minutes, titrated to pain, with monitoring of respiratory rate and sedation; reduce the dose in older adults and renal impairment. Analgesia does not mask the diagnosis and should not be withheld.
• Ibuprofen 400 mg orally every 8 hours or diclofenac 50 mg orally every 8 hours (maximum 150 mg daily) once bleeding and surgical causes are controlled and no contraindication exists (peptic ulcer, renal impairment, heart failure, anticoagulation, pregnancy over 28 weeks).
• Ondansetron 4 mg intravenously or orally every 8 hours for nausea (maximum 16 mg daily; check the QT interval and avoid with long QT syndrome).

Ectopic pregnancy

• Ruptured or unstable: immediate resuscitation and surgery (laparoscopic salpingectomy, or laparotomy when unstable).
• Stable, unruptured, no foetal cardiac activity, mass under 35 mm and beta hCG under 5000 IU/L: methotrexate 50 mg/m2 body surface area intramuscularly as a single dose (a second dose is given if beta hCG falls by less than 15% between day 4 and day 7; up to three doses). Check full blood count, renal function and liver function before; avoid NSAIDs, folic acid, alcohol, live vaccines and sun exposure; contraindicated with breastfeeding, active infection, severe renal, hepatic or haematological disease, and haemodynamic instability. Check beta hCG on day 4 and day 7, then weekly until undetectable. Advise avoiding conception for 3 months.
• Expectant management for a small ectopic pregnancy with falling beta hCG under about 1000 IU/L, with close follow up.
• Salpingostomy in women with a single remaining tube or contralateral damage who wish future fertility (risk of persistent trophoblast, so follow beta hCG weekly).

Ovarian torsion. Urgent laparoscopy for detorsion, preserving the ovary whenever possible even when it appears dusky; oophoropexy and cystectomy as indicated. Do not wait for Doppler or imaging to exclude torsion when suspicion is high.

Pelvic inflammatory disease

• Outpatient: ceftriaxone 1 g intramuscularly once, doxycycline 100 mg orally twice daily for 14 days, and metronidazole 400 mg orally twice daily for 14 days. Review at 72 hours.
• Admit for severe illness, vomiting, pregnancy, tubo ovarian abscess or failed outpatient treatment: ceftriaxone 2 g intravenously once daily, doxycycline 100 mg orally or intravenously twice daily, and metronidazole 500 mg intravenously every 8 hours; change to oral therapy after 24 hours of clinical improvement to complete 14 days. Alternative: clindamycin 900 mg intravenously every 8 hours plus gentamicin 5 to 7 mg/kg intravenously once daily adjusted to kidney function and levels.
• Tubo ovarian abscess over 7 cm or not responding to antibiotics in 48 to 72 hours: drainage under ultrasound or CT control, or laparoscopy.
• Remove an intrauterine device if there is no response at 72 hours. Treat partners, avoid intercourse until treatment is complete, and test for HIV, syphilis and hepatitis B.

Miscarriage and retained products

• Incomplete or missed miscarriage in a stable woman: misoprostol 800 microgram vaginally (or 600 microgram orally) as a single dose, repeated after 24 to 48 hours if needed; contraindicated with suspected ectopic pregnancy, sepsis and severe haemorrhage; or surgical evacuation.
• Septic miscarriage: broad spectrum intravenous antibiotics (ceftriaxone 2 g intravenously once daily with metronidazole 500 mg intravenously every 8 hours, adding gentamicin 5 mg/kg once daily when severe), and urgent evacuation of the uterus.

Appendicitis. Urgent surgical assessment; ceftriaxone 2 g intravenously daily with metronidazole 500 mg intravenously every 8 hours before appendicectomy.

Cysts and other gynaecological causes. Ruptured or haemorrhagic ovarian cyst: analgesia and observation, with surgery for haemodynamic instability or falling haemoglobin. Fibroid degeneration:

NSAIDs and analgesia. Ovarian hyperstimulation: fluids, analgesia, thromboprophylaxis with enoxaparin 40 mg subcutaneously daily, specialist care. Endometriosis: NSAIDs and hormonal therapy.

Other causes. Ureteric colic: diclofenac 75 mg intramuscularly or 50 mg orally every 8 hours (maximum 150 mg daily), with urology referral for stones over 5 mm, infection, obstruction or solitary kidney. Pyelonephritis: ceftriaxone 1 to 2 g intravenously once daily, switching to oral antibiotics by culture result. Bowel obstruction or perforation: surgical referral. Diverticulitis: antibiotics and surgical review.

Special groups. Pregnancy: avoid NSAIDs after 28 weeks and in the first trimester when possible, use paracetamol and short courses of morphine, treat appendicitis surgically, and involve the obstetric team early. Girls: paediatric surgical and gynaecological assessment; low threshold for laparoscopy. Postmenopausal women: low threshold for CT and for gynaecological oncology referral when a mass is found.

Monitoring. Repeat vital signs and abdominal examination at least hourly while unstable, then every 4 hours. Monitor haemoglobin, beta hCG and urine output. Review at 72 hours when treated as an outpatient.

Referral and escalation. Refer to the on call gynaecology team the same day for ectopic pregnancy, torsion, tubo ovarian abscess, pelvic inflammatory disease not responding at 72 hours, or any unstable woman. Refer to general surgery for appendicitis, obstruction or peritonitis. Refer to urology for obstructed or infected stones. Refer to early pregnancy assessment services for pregnancy of unknown location and miscarriage.

Admission criteria. Haemodynamic instability, suspected ectopic pregnancy or torsion, peritonism, severe pelvic inflammatory disease, abscess, uncontrolled pain, pregnancy with significant pain or bleeding, and sepsis.

Discharge and follow up. Discharge only when pregnancy of unknown location has a follow up plan, pain is controlled, and the woman can return within 24 hours. Arrange repeat beta hCG at 48 hours, review of results, and gynaecology follow up.

Safety netting. Return the same day for worsening or sudden severe pain, shoulder tip pain, fainting, heavy bleeding, fever, vomiting, or inability to pass urine.