OG14.1-3,OG15.1-2 | Abnormal and Operative Obstetrics — Glossary

A line on the partograph drawn 4 hours to the right of the alert line; a cervicograph crossing this line demands an immediate management decision (augmentation, referral, or operative delivery).

A protocol of early amniotomy, strict monitoring of cervical dilatation, and use of oxytocin augmentation when progress falls below 1 cm/h in the active phase — applicable only when obstruction has been excluded.

The diagonal line on the partograph representing the expected minimum rate of cervical dilatation (1 cm/h) from active phase onset; crossing it signals the need for closer monitoring.

The principle that forceps traction must be directed along the curve of the birth canal (axis of the pelvis) at each phase of delivery — initially downward and backward, then outward and upward as the head emerges.

A transverse groove on the maternal abdomen marking the junction between the thickened, retracted upper uterine segment and the thinned, overstretched lower segment; its upward migration signals imminent uterine rupture.

The pathological retraction ring between the upper and lower uterine segments that rises progressively during obstructed labour; its disappearance during a previously obstructed labour signals that rupture has occurred.

A presentation in which the sinciput (forehead) is the lowest fetal part, presenting the largest head diameter (mentovertical ~13.5 cm); almost always requires caesarean section.

A method of delivering the aftercoming head in vaginal breech delivery: the infant's feet are held and swung in an arc upward while an assistant applies suprapubic pressure to flex and deliver the head.

Oedema of the presenting fetal scalp caused by prolonged pressure and venous obstruction at the cervix; graded 0 to +++ and can give a false impression of greater descent on vaginal examination.

Subperiosteal haemorrhage after instrumental or difficult delivery; presents as a firm, well-defined swelling that does not cross suture lines; resolves spontaneously but may cause neonatal jaundice.

A mechanical mismatch between the fetal head and the maternal pelvis that prevents descent; absolute CPD means no vaginal delivery is possible; relative CPD may respond to optimal positioning and labour augmentation.

The inability of the uterine cervix to retain a pregnancy in the second trimester, characterised by painless progressive dilatation and effacement without contractions; the main indication for cervical cerclage.

The plotted curve of cervical dilatation over time on the partograph; its relationship to the alert and action lines guides clinical decision-making in labour.

A temporary caput succedaneum (localised swelling and skin bruising) on the neonatal scalp created by vacuum cup application; resolves spontaneously within 24–48 hours and requires only parental reassurance.

A caesarean section using a vertical (classical) midline incision in the upper uterine body; now rarely performed; associated with a 4–9% rupture risk in subsequent labour — absolute contraindication to VBAC.

Breech presentation with both hips and both knees flexed, resembling a cannonball position; buttocks and feet present together (~10%).

Rupture through all layers of the uterine wall including the visceral peritoneum, with free communication between the uterine cavity and the peritoneal cavity; associated with catastrophic haemorrhage and fetal extrusion.

A pelvis in which one or more diameters are reduced below the minimum required for normal vaginal delivery; the most common cause of obstructed labour in low-resource settings, often linked to nutritional deficiency.

The obstetric stage at which the widest diameter of the fetal presenting part (typically 3–4 cm) is visible at the vaginal introitus without retraction between contractions; the correct moment for episiotomy.

The time between the decision to perform emergency CS and delivery of the fetus; for Category 1 (immediate threat to life) the target is within 30 minutes; VBAC facilities must maintain this capability.

The time from decision to perform emergency CS to delivery of the fetus; Category 1 (immediate threat to life) target is within 30 minutes; a key quality indicator in maternity care.

The bony reference point on the fetal presenting part used to describe position: occiput (vertex), mentum/chin (face), sinciput (brow), sacrum (breech), acromion (shoulder).

An obstetric procedure (e.g. craniotomy, cleidotomy) performed to reduce the size of a dead fetus to allow vaginal delivery when LSCS is unavailable or contraindicated; performed only by trained operators.

A deliberate surgical incision of the perineum and posterior vaginal wall made during the second stage of labour to enlarge the vaginal outlet; classified as mediolateral or midline based on direction.

The striated voluntary muscle encircling the anal canal; its injury (partial or complete) defines a third-degree perineal tear; subclassified as 3a (<50% thickness), 3b (>50% or complete), or 3c (EAS + internal anal sphincter).

A procedure performed from 36–37 weeks gestation in which the obstetrician uses external abdominal manipulation to turn a breech or transverse fetus to a cephalic presentation; success rate ~50–60%.

The optimal placement site for the vacuum cup, located approximately 3 cm anterior to the posterior fontanelle (1 cm behind the anterior fontanelle) in the midline of the sagittal suture; cup placement here promotes flexion and synclitism.

Breech presentation with one or both feet presenting below the buttocks (incomplete breech); associated with the highest cord prolapse risk among breech types (~25% of breeches).

An instrumental delivery technique using metal blades applied bilaterally to the fetal head; the blades lie in the pelvic transverse diameter, gripping the parietal eminences, and traction is applied downward and forward.

Breech presentation in which the hips are flexed and the knees extended, so the legs lie straight against the fetal abdomen; the commonest breech type (~65%), and the most favourable for vaginal breech delivery.

A woman who has had five or more previous deliveries; associated with myometrial thinning, abnormal placentation (praevia, accreta), and increased risk of uterine rupture during labour.

Blood in the urine during labour, detectable in the urinary catheter bag; a key clinical warning sign of bladder or LUS involvement in uterine scar rupture.

Inappropriate use of oxytocin (too high a dose, in the presence of obstruction, malpresentation, or scar) that generates excessive intrauterine pressure and can precipitate uterine rupture.

The involuntary smooth muscle continuation of the circular rectal wall; responsible for approximately 80% of resting anal tone; injury is classified 3c when combined with EAS disruption.

Bleeding into the peritoneal cavity from uterine rupture; presents as haemodynamic shock with a soft, silent abdomen and minimal vaginal bleeding — the internal haemorrhage is not externally visible.

A straight transverse skin incision 3 cm above the pubic symphysis used for LSCS entry; associated with faster entry and lower complication rates than the Pfannenstiel incision in randomised trials.

Rotational obstetric forceps with a minimal pelvic curve and a sliding lock mechanism, designed for rotation and delivery of the fetal head in malrotation (occipito-posterior or deep transverse arrest).

A technique for delivering the shoulders in vaginal breech delivery: the fetal trunk is rotated 180° to bring the posterior shoulder (which is above the promontory) to the anterior, allowing each arm to be swept down.

The passive, thinner lower portion of the uterus formed in late pregnancy and early labour; it is increasingly stretched during obstructed labour and is the site of most LSCS incisions.

The transverse incision made in the lower, thin part of the uterus during LSCS; preferred because this segment is poorly contractile, bleeds less, and heals with a stronger scar than a classical upper-segment incision.

The standard modern CS using a transverse incision in the lower uterine segment; the resulting scar has a ~0.5–1% rupture risk in subsequent labour, much lower than a classical scar.

An abnormal position of a vertex presentation — the occiput is not in the expected anterior position; occipitoposterior is the most common malposition.

Any presentation of the fetus other than vertex (the occiput of the fetal skull); includes breech, face, brow, shoulder, and compound presentations.

A technique for delivery of the aftercoming head in vaginal breech delivery: the operator's index and middle fingers are placed on the fetal malar bones (to flex the head), while the body rests on the forearm and traction is applied to the fetal jaw.

A cervical cerclage technique using a purse-string suture placed around the ectocervix at the level of the internal os; the knot is tied anteriorly and is accessible for elective removal at 36–37 weeks.

An episiotomy incision directed 45–60° from the midline toward the ischiorectal fossa, reducing the risk of extension to the anal sphincter compared with midline incision.

A face presentation in which the fetal chin (mentum) faces anteriorly toward the maternal pubic symphysis; vaginal delivery is possible as the head can deliver by flexion once the chin passes under the symphysis.

A face presentation in which the fetal chin faces posteriorly toward the maternal sacrum; the head cannot flex further (already maximally extended), making vaginal delivery impossible — caesarean section is required.

The overlapping of fetal skull bones at the suture lines to reduce the presenting diameter; graded 0 to +++, with grade +++ (irreducible overlap) indicating severe, prolonged obstruction.

Failure of descent of the presenting part despite adequate uterine contractions, due to a mechanical barrier between the fetus and the maternal pelvis or soft tissue.

A vertex presentation in which the fetal occiput faces the maternal sacrum rather than the pubic symphysis; associated with prolonged, painful labour; majority rotate spontaneously to OA during labour.

Delivery of the fetus through the vaginal canal using instruments — forceps or vacuum extractor — to assist maternal effort when spontaneous delivery is not possible or is unsafe.

A component of forceps traction technique in which the operator simultaneously applies downward traction on the shanks and outward pull on the handles to align traction with the pelvic axis, following the curve of Carus.

A single-sheet graphical record of labour progress (cervical dilatation, fetal descent, contractions, fetal heart rate, vital signs) used to detect deviation from normal labour and guide clinical action at the alert and action lines.

A pyramidal fibromuscular structure at the centre of the perineum where the bulbospongiosus, transverse perinei, and external anal sphincter converge; the key structure reconstituted during perineal repair.

Irrigation of the peritoneal cavity with warm saline at laparotomy to remove clotted blood and amniotic fluid after uterine rupture; reduces the risk of peritonitis in contaminated cavities.

A curved transverse skin incision made 2 cm above the pubic symphysis, following the natural skin crease; cosmetically superior and widely used for LSCS.

A synthetic absorbable braided suture, absorbed over 56–70 days; the standard suture for episiotomy and perineal tear repair, used as 2/0 or 3/0 on appropriate curved needles.

Regional anaesthesia of the pudendal nerve (S2–S4) achieved by infiltrating local anaesthetic (1% lignocaine) just medial to the ischial spine; provides analgesia for perineal repair and outlet operative delivery when epidural is unavailable.

A mandatory digital examination of the rectum performed after every episiotomy or perineal tear repair to confirm that no sutures have inadvertently penetrated the rectal mucosa, preventing fistula formation.

Incomplete separation of a previous uterine incision scar (myometrium tears but visceral peritoneum remains intact); often asymptomatic or associated with subtle CTG changes; discovered at repeat CS.

A submucosal cervical cerclage in which vaginal mucosa is incised and the suture is placed at a higher level than the McDonald technique; technically more demanding, often requires CS for delivery as the knot is buried.

A dangerous neonatal complication of vacuum extraction in which blood accumulates between the periosteum and the galea aponeurotica; it can cross suture lines, is not limited by bone, and may contain the entire neonatal blood volume.

Haemorrhage into the subaponeurotic space of the scalp; a potentially fatal neonatal complication of vacuum extraction recognised by a diffuse, fluctuant, expanding scalp swelling that crosses suture lines; can contain the entire neonatal blood volume.

Surgical removal of the uterine body while leaving the cervix in place; faster than total hysterectomy and preferred in haemodynamically unstable patients with uterine rupture when the tear does not extend to the cervix.

Surgical division of the pubic symphysis to increase pelvic dimensions and allow vaginal delivery; rarely performed in modern practice, used in low-resource settings as an alternative to LSCS for obstructed labour with a live fetus.

Normal alignment of the fetal head in which the sagittal suture is equidistant from the pubic symphysis and the sacrum; asynclitism (lateral tilting) increases the effective presenting diameter and makes both spontaneous and instrumental delivery more difficult.

A fetal lie in which the fetal long axis is perpendicular to the maternal long axis; the shoulder or acromion presents, cord prolapse risk is high, and caesarean section is required unless ECV succeeds.

Planned attempt at vaginal birth in a woman with a previous caesarean section; success rate ~60–70% for appropriate candidates with a transverse LUS scar; requires continuous CTG and immediate CS capability.

Tearing of the uterine wall (complete = all layers including peritoneum; incomplete/dehiscence = myometrium only) occurring during pregnancy or labour; a surgical emergency.

Any drug that causes uterine contraction; used to manage the third stage of labour and prevent or treat postpartum haemorrhage; examples include oxytocin (first-line), ergometrine (contraindicated in hypertension), misoprostol, and carboprost (contraindicated in asthma).

An instrumental delivery technique using a suction cup applied to the fetal scalp at the flexion point; traction is applied with contractions and maternal pushing to complete delivery of the vertex.

Vaginal birth after caesarean — the successful outcome of a TOLAC; associated with lower maternal morbidity than elective repeat CS if it succeeds, but uterine rupture risk of ~0.5–1%.

The peritoneal fold between the anterior uterine wall and the bladder, incised at lower-segment CS to reflect the bladder downward and expose the lower uterine segment.

An abnormal communication between the bladder and vagina resulting from ischaemic necrosis caused by prolonged pressure of the fetal head in obstructed labour; a devastating long-term sequel.