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Lecture 1: Abnormal Position & Presentation

7th Oct 2012

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ABNORMAL POSITION & PRESENTATION

By Dr Aly Kholeif

OCCIPITOPOSTERIOR POSITION

- Right OP> Left OP

- During pregnancy (30-40%) > approached labour (10-15%) due to correction spontaneously

Etiology

1. Android pelvis: suspect this for every primi gravida

2. Lumbar kyphosis : of less importance

3. Pendulous abd

Diagnosis

A. Abdominally

1. Loss of curvature /flatten contour

2. fundal level (dt delayed engagement in such position)

3. Fetal back not easily defined

4. Delayed engagement of fetal head dt deflexion

5. U/s dx position easily

B. Vaginally (late in labour)

1. ant frontanelle felt easily towards iliopectineal eminence

2. post frontanelle felt difficult towards sacroiliac joint

Fate of OP (mech of labour)

1. Spontaneous vaginal delivery (mostly) thru long anterior/ short post rotation

* Deflexion= loss of full flexion giving different diameter of engagement

*Main cause of deflexion= when fetal descend biparietal diam has some resistance result in rotate

& deflexion as anterior part can passed easily (8-12 cm)

* Biparietal diameterdeflexiondelayed engagementMay lead to PROM* Biparietal diam = 9.5cm

* Ant biparietal diam= 8 cm

a) long ant rotation of occiput (90%) & delivered spontaneously(minimal complications)

b) short post rotation of occiput (4%) (face to pubis) (with some complications)

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2. failure of spontaneous vaginal delivery dt short ant rotation (deep TS arrest/persistent OP)

3. Secondary face presentation (head fully extended)

4. Secondary brow presentation

Factors affect Mechanism/ Good Omens/ Predisposing Factors

1. Good uterine action

2. Intact membranes

3. Good shape & size of pelvis/ roomy pelvis

4. Average size of fetal head

5. degree of deflexion of fetal head (causes of deflexion)

Bad Omens

1. Rupture membranes

2. Contracted pelvis

3. Weak uterine action

4. Big head of fetus

a) incomplete ant rotation (deep TS arrest) x spontaneous deliverydt occipito frontal (11.25 cm) >

interspinous diam (10.5cm) cannot passed thru

b) non rotation of occiput (persistent OP)x spontaneous delivery

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Complications

1. Prolonged labour (up to 24 hours)

2. Prom

3. Perineal tears (mostly in face to pubis)

*Prognosis= 90% of cases good progno (deliver spontaneously)

Management

1. Prevention of PROM by minimize vaginal exam

2. Wait for spontaneous long anterior/ short post rotation for spontaneous delivery (good omens)

3. Failure of spontaneous delivery dt deep TS arrest/ persistent OP managed thru:

a) Manual rotation anesthesia ORb) Forceps under anaesthesia :

Test impaction (raising head upwards) Manual rotation Do some degree of flexion

c) Rotation/ extraction with vacuum extractord) C/S safer

* no complication in long anterior rotation as it is like normal delivery

*complications more in:

1. short post during vaginal delivery

2. occiput arrested

3. deep TS arrest

*Triad/Syndrome of OP

Sluggish UT

PROM perineal tears

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FACE PRESENTATION

Def: Cephalic present with complete extended fetal head

Etiological types

1. 1ry face (before onset of labour):

a. Fetal causes

Anencephaly Fetal thyroid tumours Loop of umbilical cord around neck

b.Maternal causes

Flat pelvis Pendulous abdomen

2. 2ry face (after onset of labour) More common (as congenital anomalies=1ry face are less common to occur) 2ry to OP

* Anencephaly triad face presentation

Polyhydramnios passed due date

Positions

Mentum is denominator LMA (commonest) dt 2ry caused (LOP)

Mech of Labour

Engaging diameter:

Mento anterior-spontaneous delivery Mento posterior-undelivered mostly

* as the post wall of pelvis is long & head is fully extended, chest has to enter the pelvis with

Head when position is mento-post & bulk of cranium is delayed by SP

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Positions

1st

- R.M.P

2nd

L.M.P

3rd L.M.A

4th R.M.A

Management

1. mento ant= wait & see if it rotates

2. mento post = CS is a must unless there is

Strong contraction Roomy pelvis Small sized / premature fetus

BROW PRESENTATION

Def= Cephalic with head midway between flexion & extension

Engaging diameter longest is mento vertical diam (13.5cm) x spontaneous delivery at all CS

Positions

1. fronto ant

2. Fronto post

DDx

With face presentation W/out face presentation1. orbital margin

2. root of nose

3.ala nasi

4. mentum (x ant frontanelle)

1. no mentum

2. ant frontanelle by vaginal exam

Types of Brow Presentation

1. Transient

2. Persistent

Documents

1) abn P&P (7.10.12)