Obstructed Labour & Rupture Uterus
Obstetrics & Gynaecology · Labour · lean revision notes
Obstructed Labour & Rupture Uterus
Obstructed labour is a labour in which, despite good uterine contractions, the presenting part fails to descend because of a mechanical barrier. Left unrelieved, it culminates in maternal exhaustion, sepsis, fistula formation, and the dreaded rupture uterus — a leading cause of preventable maternal death in low-resource settings. This pairing is a perennial NEET PG favourite, especially the contrast between Bandl's ring and the physiological retraction ring, and the recognition of impending versus complete rupture.
Definition & Concept
Obstructed labour = arrest of descent of the presenting part owing to a mechanical obstruction, in the presence of effective uterine activity. The cervix is usually fully (or nearly fully) dilated, and labour has been prolonged.
Distinguish two related but separate entities:
- Obstructed labour — mechanical bar to descent despite strong contractions (cervix often fully dilated). This is an emergency.
- Prolonged labour / failure to progress — slow cervical dilatation or descent; obstruction is one cause but not the only one (inefficient uterine action, malposition).
High-yield: In obstructed labour the uterus contracts strongly and progressively harder against the obstruction — this is the basis of the dangerous tonic retraction that leads to rupture. Contrast with secondary uterine inertia, where contractions weaken with maternal exhaustion (common in primigravida).
Etiology of Obstructed Labour
Causes are best remembered by the Passages, Passenger, Power framework — with obstruction lying in passages or passenger.
| Category | Specific causes |
|---|---|
| Faulty passages (maternal) | Contracted/android pelvis, cephalopelvic disproportion (CPD), pelvic tumours (cervical/ovarian/fibroid in pouch of Douglas), stenosis, full bladder/rectum |
| Faulty passenger (fetal) | Malpositions (deep transverse arrest, persistent occipito-posterior), malpresentations (brow, shoulder/transverse lie, mentoposterior face, breech with extended arms), hydrocephalus, locked twins, fetal macrosomia, conjoined twins |
| Other | Soft tissue: cervical dystocia, vaginal septum, Bandl's ring constriction |
High-yield: Shoulder presentation (transverse lie) in labour and brow presentation are classic causes of obstructed labour in exams. A neglected shoulder presentation with prolapsed arm = the prototype of obstructed labour leading to rupture.
Most common cause overall = cephalopelvic disproportion. Most common malpresentation causing obstruction = transverse lie / shoulder presentation.
Pathophysiology — How Obstruction Leads to Rupture
The mechanics are heavily tested. As labour is obstructed:
- The upper uterine segment retracts and thickens progressively (active segment).
- The lower uterine segment stretches and thins to accommodate the fetus driven downward.
- The junction between thick upper and thin lower segment rises abnormally high and becomes palpable as a ridge — Bandl's ring (a pathological retraction ring).
- The thinned, over-stretched lower segment finally gives way → rupture uterus.
Flow: Mechanical obstruction → strong contractions → upper segment retraction + lower segment thinning → Bandl's ring rises → impending rupture → lower segment tears → complete rupture → intraperitoneal haemorrhage / shock / fetal death.
Bandl's Ring vs Physiological Retraction Ring — the classic discriminator
| Feature | Physiological retraction ring | Bandl's ring (pathological) |
|---|---|---|
| Nature | Normal | Abnormal / pathological |
| Location | Junction of upper & lower segment, low | Rises high, towards/above umbilicus |
| Visibility | Not visible/palpable externally | Visible & palpable as oblique transverse ridge across abdomen |
| Significance | Normal labour mechanics | Sign of obstructed labour / impending rupture |
| Lower segment | Normal thickness | Grossly thinned, tender |
High-yield: A transverse/oblique groove across the lower abdomen rising towards the umbilicus in a woman in obstructed labour = Bandl's ring = impending rupture. The uterus assumes an hour-glass shape.
Clinical Features of Obstructed Labour
- Prolonged labour; cervix fully or nearly fully dilated but no descent.
- Maternal distress, dehydration, ketoacidosis, tachycardia, pyrexia (infection).
- Excessive moulding (3+) and large caput on the fetal head.
- Bandl's ring palpable; tonically contracted, tender uterus (uterus does not relax fully between pains).
- Vulval oedema; scanty, hot, dry vagina; foul-smelling discharge if infected.
- Oedematous, congested cervix; the bladder base may be drawn up — risk of vesicovaginal fistula from pressure necrosis.
- Fetal signs: fetal distress → fetal death (meconium, FHS irregular/absent), large caput, overlapping sutures.
- In neglected shoulder presentation: prolapsed pulseless oedematous arm, shoulder impacted in pelvis.
High-yield: The triad of a tonically retracted tender uterus, Bandl's ring rising to the umbilicus, and haematuria/blood-stained urine signals impending rupture — proceed to immediate delivery, never to oxytocin.
Rupture Uterus
Classification
| Basis | Types |
|---|---|
| Timing | During pregnancy vs during labour (most common) |
| Causation | Spontaneous, traumatic (instrumental/obstetric manoeuvres), scar rupture |
| Depth | Complete (whole thickness incl. peritoneum → communicates with peritoneal cavity) vs Incomplete (peritoneum intact; rupture confined, often broad ligament haematoma) |
| Site | Lower segment (commonest in scar rupture and obstructed labour) vs upper segment |
Etiology of Rupture Uterus
- Scar rupture (commonest cause overall in developed/scarred-uterus settings): previous LSCS, classical CS (highest risk), myomectomy, hysterotomy, prior rupture repair.
- Obstructed labour (commonest cause in unscarred uterus in developing countries).
- Injudicious oxytocin/prostaglandin use (hyperstimulation), especially with obstruction or grand multiparity.
- Obstetric manoeuvres / instrumentation: internal podalic version, forceps, destructive operations, manual removal of placenta, fundal pressure.
- Grand multiparity (thin, fibrotic myometrium).
High-yield: A classical (upper-segment vertical) scar has the highest rupture risk and can rupture before labour, in late pregnancy, often silently. A lower-segment transverse scar is the safest and usually ruptures during labour. This scar-type comparison is a repeated MCQ.
Risk with Scar Rupture — quick figures
| Scar type | Approx. rupture risk |
|---|---|
| Lower segment transverse | ~0.2–0.7% |
| Classical (upper vertical) | ~4–9% |
| Inverted-T / J | ~4–9% |
| Prior single LSCS undergoing TOLAC | ~0.5% |
Impending vs Complete (Scar vs True) Rupture — must-know comparison
| Feature | Impending rupture | Complete rupture |
|---|---|---|
| Uterine contractions | Strong, tonic, no relaxation | Suddenly cease (after a tearing pain) |
| Pain | Continuous lower abdominal pain, tender | Sudden sharp tearing abdominal pain, then relief |
| Bandl's ring | Rising towards umbilicus | May disappear once ruptured |
| Maternal pulse/BP | Tachycardia, restlessness | Shock: thready pulse, hypotension, pallor |
| Haematuria | Present (bladder involvement) | Frank haematuria |
| Fetal heart | Distress, may be present | Usually absent (fetal death) |
| Abdominal palpation | Tonically contracted uterus | Easily palpable fetal parts (fetus extruded into peritoneal cavity), uterus felt as separate firm mass beside the fetus |
| Vaginal exam | Presenting part high/impacted | Presenting part recedes / rises up (loss of station) |
High-yield: The classic exam clue for complete rupture = sudden cessation of contractions + recession of the presenting part + easily palpable fetal parts under the abdominal wall + maternal shock + vaginal bleeding. Scar rupture is often less dramatic — may present as scar tenderness, fetal bradycardia (the most reliable/earliest sign of scar dehiscence is abnormal CTG / fetal heart rate abnormality), and mild bleeding.
Mnemonic for warning signs of scar rupture in labour: "SCAR" — Scar tenderness/pain, CTG abnormality (fetal bradycardia — earliest), Abnormal vaginal bleeding/haematuria, Recession of presenting part + maternal tachycardia/hypotension.
Diagnosis & Investigations
- Primarily clinical — diagnosis in an emergency setting rests on the bedside picture above. Do not delay treatment for imaging.
- Continuous CTG / fetal heart monitoring — fetal heart rate abnormality (prolonged deceleration / bradycardia) is the single most sensitive sign of scar rupture in a labouring woman with a prior CS.
- Ultrasound — may show free intraperitoneal fluid (haemoperitoneum), extruded fetus, or scar defect; useful when diagnosis uncertain but not to be awaited in an unstable patient.
- Bloods — haemoglobin/haematocrit (falling), cross-match, coagulation profile, blood group.
- Catheterisation — frank haematuria suggests bladder involvement.
Investigation of choice for confirming uncertain cases / antenatal scar dehiscence = ultrasonography. Best monitoring tool in TOLAC = continuous electronic fetal monitoring (CTG).
Management
A. Obstructed labour (no rupture yet)
General + definitive:
- Resuscitate: IV fluids, correct dehydration/ketoacidosis, broad-spectrum antibiotics, catheterise bladder, blood arranged.
- Definitive treatment = deliver immediately by the safest route.
- Caesarean section is the treatment of choice in most cases — alive fetus, transverse lie, brow, CPD.
- If fetus is dead and conditions are favourable (fully dilated, no impending rupture), a destructive operation (e.g. craniotomy for cephalic, decapitation for impacted shoulder) may be considered by an experienced operator — but CS is increasingly preferred to avoid maternal injury.
High-yield: In established obstructed labour, oxytocin is absolutely contraindicated — it precipitates rupture. The answer to "obstructed labour with transverse lie / Bandl's ring" is emergency caesarean section, not augmentation.
B. Rupture uterus
Flow: Resuscitate (2 wide-bore cannulae, crystalloids, blood/blood products, treat shock) → immediate laparotomy → deliver fetus & placenta → control haemorrhage → decide repair vs hysterectomy.
Surgical options at laparotomy:
| Procedure | When chosen |
|---|---|
| Rupture repair (rent suturing) | Clean, recent, lower-segment tear; young woman desiring fertility; haemodynamically stable |
| Repair + tubal ligation | Repairable tear but family complete / high recurrence risk |
| Subtotal (supracervical) hysterectomy | Extensive lower-segment tear, uncontrolled bleeding, life-saving need for speed |
| Total hysterectomy | Tear extending to cervix/vagina or involving cervix |
- Ligate uterine/internal iliac arteries if bleeding persists; check bladder and ureters for injury and repair.
- Post-op: continued antibiotics, anticoagulation prophylaxis, ICU monitoring.
High-yield: Choice between repair and hysterectomy depends on extent of rupture, haemodynamic stability, infection, and desire for future fertility. A ragged, infected, or cervix-extending tear → hysterectomy; a clean recent lower-segment rent in a young woman → repair (± sterilisation).
Complications
Maternal
- Haemorrhagic shock, DIC, death (rupture is among top direct causes of maternal mortality in obstructed labour).
- Obstetric fistula — vesicovaginal (VVF, most common) / rectovaginal — from pressure necrosis (classic late complication of neglected obstructed labour).
- Puerperal sepsis, peritonitis.
- Bladder/ureteric/bowel injury during surgery.
- Loss of fertility (hysterectomy); secondary infertility, Asherman-like sequelae.
- Postpartum haemorrhage, paralytic ileus.
Fetal
- Intrauterine death, birth asphyxia, hypoxic-ischaemic encephalopathy, intracranial haemorrhage, sepsis, fracture/nerve injury from manoeuvres.
High-yield: Vesicovaginal fistula developing days after a difficult/neglected labour = pressure necrosis of the bladder base trapped between fetal head and pubic symphysis. Prolonged second stage is the key antecedent.
Prevention
- Good antenatal care: detect malpresentation, CPD, prior scars early; plan delivery.
- Use of the WHO partograph — crossing the alert line prompts referral and the action line prompts intervention; partographic surveillance is the single most effective tool to prevent obstructed labour and rupture.
- Avoid injudicious oxytocin, especially in grand multiparas and suspected obstruction.
- Careful patient selection and continuous CTG in TOLAC; avoid VBAC in classical scar.
- Timely caesarean for transverse lie, brow, severe CPD.
Key Differentials
When a labouring woman collapses with abdominal pain and shock, consider:
| Condition | Distinguishing pointer |
|---|---|
| Rupture uterus | Cessation of contractions, recession of presenting part, fetal parts easily felt, prior scar/obstruction |
| Abruptio placentae | "Woody-hard" tender uterus, revealed/concealed bleeding, hypertension, uterus still contracting, fetal parts NOT easily felt |
| Placenta praevia | Painless bleeding, soft uterus, no shock disproportionate to loss |
| Amniotic fluid embolism | Sudden collapse, hypoxia, DIC, often at peak of contractions, no recession of part |
| Concealed haemorrhage / broad-ligament haematoma | Shock out of proportion to visible bleeding, lateral uterine mass |
High-yield: Abruption vs rupture — in abruption the uterus remains hard and contracting and fetal parts are difficult to feel; in rupture the uterus relaxes, contractions stop, and fetal parts become easily palpable. This is a classic two-option MCQ.
Recently asked / exam angle
- Bandl's ring identification and its differentiation from the physiological retraction ring (location, palpability, significance) — repeatedly asked image/clinical vignettes.
- "Strong contractions + no descent + ring rising to umbilicus" → diagnosis = impending rupture / obstructed labour; next step = emergency CS (NOT oxytocin).
- Earliest/most reliable sign of scar rupture in TOLAC = fetal heart rate abnormality (bradycardia) on CTG.
- Highest-risk scar for rupture = classical (upper segment vertical); can rupture antenatally.
- Commonest cause of rupture in unscarred uterus = obstructed labour; commonest cause overall (scarred) = previous caesarean scar.
- Surgical decision: clean lower-segment tear in young woman → repair; extensive/cervix-extending tear → hysterectomy.
- VVF as a late sequela of neglected obstructed labour — mechanism (pressure necrosis) and most common type.
- Differentiate rupture from abruption by uterine tone and palpability of fetal parts.
- Drug/intervention contraindicated in obstructed labour = oxytocin.
Rapid revision
- Obstructed labour = mechanical bar to descent despite strong contractions, cervix usually fully dilated.
- Commonest cause = CPD; classic malpresentations = transverse lie / shoulder, brow.
- Bandl's ring = pathological retraction ring rising towards the umbilicus → impending rupture; uterus shows hour-glass shape.
- Physiological retraction ring is normal, low, and not palpable externally.
- Oxytocin is contraindicated in obstructed labour — it causes rupture.
- Definitive treatment of obstructed labour with live fetus = emergency caesarean section.
- Complete rupture = sudden cessation of pains + recession of presenting part + easily palpable fetal parts + shock + vaginal bleeding.
- Classical scar = highest rupture risk, may rupture antenatally; lower-segment transverse scar = safest, ruptures in labour.
- Earliest/most reliable sign of scar rupture in TOLAC = fetal bradycardia (CTG abnormality).
- Rupture management: resuscitate + blood → immediate laparotomy → repair vs hysterectomy based on extent, stability, fertility wish.
- Abruption (hard uterus, fetal parts not felt) vs rupture (relaxed uterus, fetal parts easily felt) — key discriminator.
- Neglected obstructed labour → vesicovaginal fistula (pressure necrosis); prevent with the WHO partograph (alert & action lines).