The sixth batch of Mansoura Manchester programme

The sixth batch of Mansoura Manchester programme
Professor: Alaa Mosbah , Mansoura Manchester programme

Friday, December 28, 2007

Contracted pelvis and cephalopelvic disproportion

Contracted pelvis and cephaopelvic disproportion Definition: a contracted pelvis is a pelvis whose shape and size are sufficiently abnormal to cause difficulty in vaginal delivery of normal (average size body ) This may occurs when : 1- One or more of the pelvic diameters is reduced enough to cause dystochia (Obstetric definition) 2- One or more of the pelvic diameters is reduced below the average by on or more centimeters (antatomical definition) CPD: or fetopelvic disproportion in presentations other than cephalic) can arise from either : 1- Diminished pelvic capacity 2- Excessive fetal size or abnormal fetal development Or more usually a combination of both In contemporary obstetric practice dystochia literally means difficult labour and is characterized by abnormal progress by labour Generally this can occurs as a result of 3 distinct causes that may exist singly in combination 1- Abnormalities in the power: a. Uterine contractility (uterine dysfunction in significantly strong or inappropriately coordinated to affect the dilate the cervix = dysfunctional labour) b. Inadequately voluntary maternal expulsive effort during the 2nd stage of labour 2- Abnormalities in the passenger: a. Abnormal presentation and / or position b. Abnormal fetal development (congenitally malformed baby) 3- Abnormalities in the passage : a. Abnormalities in size or shape of the bony pelvis (contracted pelvis) b. Abnormalities of soft tissues of the reproduction tract and other pelvic organs (soft tissue obstruction) Classification of contracted pelvis A - Pelvic inlet contraction : when the shortest onteroposterioer diameter of the inlet < 10cm or when the greatest transverse diameter is < 12cm or when the brim idea Anteroposterior diameter x 100) is < 85 Transverse diameter The Anteroposterior diameter of the pelvic inlet is commonly approximated by manually measuring the diagonal conjugate which is about 1.5cm greater therefore inlet contraction id dysnied as a diagonal conjugate < 11.5cm Contracted inlet can cause: 1- delayed desert of the fetal head or primigravida until after the onset of labour if at all. (usually the head is engaging or already engaged in the least 2 weeks of pregnancy in normal nullipara before the onset of labour 2- face and shoulder presentation (3 times more frequent) 3- cord prolpase (4-6 times more frequent) NB: contracted pelvis has no relation to breach presentation 4- in contracted pelvis, rupture of membranes the absnce of preserve of the head against the cervix and the lower uterine segment predisposes to less effective uterine contractions (inertia) B- Midpelvic contraction: 1- More common that inlet contraction 2- It usually causes transverse arrest of the head resulting in difficulty or failed midforceps and increased CS rate 3- Average midpelvic measurements are: a. Transverse (interspinous) = 10.5cm b. Anteroposterior 9from the lower border of the symphysis pubis to the junction of 54- ) = 11.5cm posterioer sagittal (from midpoint of interspinous line namely the previous point of the sacrum to the junction of S4-S5= 5cm c. The definition of midpelvic contraction is not prescise as in inlet contraction d. Midpelvic is called contracted of the sum of interspinous and posterior sagittal < 13.5cm (normally 15.5cm) e. Although these is no precise manual method for measuring medpelvic diameters its suggested to be contracted if : i. The spines are prominent (under projection) ii. The pelvic side walls are convergent iii. The sacroscietic notch is narrow normally the sacrospinopus ligament should measure at least 2 fingers breath (if < 2 fingers the notch is suggested to be narrow) iv. The intertuberous diameter is narrow. Normally the relation between ineter spinous and inter tuberous diameter is constant. However a normal intertuberous interspinous diameter C- Pelvic outlet contraction: Usually defined as an interischil tuberous diameter < 8cm with consequent narrow subpubic angle Its incidence is usually about 1% Outlet contraction without concomitant midplane contraction is rare Diminution of the intertuberous diameter with consequent narrowing of the anterior saggital triangle of the outlet forces the fetal head posterioely resulting in increased incidence of perineal lacerations A contracted outlet may constitute dystocia not so much by itself as through the after associated midpelvic contraction D- Combination of both inlet and outlet contractions generally contracted pelvis (just-minor pelvis) Etiology of pelvic contraction I-Congenital : 1- Naegel's pelvis = asymmetric or obliquely contracted pelvis due to absence of one of the sacrum 2- Robert's pelvis: transversly contracted pelvis due to absence of 2 sacral 3- High assimilation pelvis: the sacrum is made of 6 dused segments 4- Low assimilation pelvis: the sacrum is made of 4 fused segments 5- Split pelvis: absent pubic bone usually associated with extopia vesica 6- Dislocation of the hip joint II- Acquired: 1- Metabolic disease : a. Rickets in which the following types of pelvis are found: i. Flat rachitic pelvis ii. Generally contracted rachitic pelvis iii. Generally contracted flat rachitic pelvis (rachitic stigmata on top of generally contracted pelvis) b. Osteomalcia : causing trirdiate or rosette shaped or peaked pelvis 2- Vertebral column disease : a. kyphasis b. scoliosis c. spondylolthesis 3- Lower limb disease : a. Resulting inmissing or shortening of one limb during childhood or adolescence before ossification of the pelvis b. This results in pelvis obliquity (coxolgic pelvis) froctuers (accidents inflammatory TB ostcomylitis) 4- Disease of the pelvic bones: a. Fractures b. Tumours of pelvic bones MECHANISM OF LABOUR IN SOME COMMON TYPES OF CONTRACTED PELVIS I- Generally contracted pelvic (justo minor) Features: 1- Commonest type of contracted pelvic usually in short women 2- It shows gynaecoid chometers but these is propotional dimination of all diameters with funneling in 20% of cases Mechanism of labour: 1- Delayed descent and engagement 2- Marked moulding and formation 3- Extreme felxsion of the head (roader obliquity) 4- Deep transverse arrest (failure of long anterior rotation ) in OP if associated with outlet contracted (20% of cases) NB: Cord proplase is rare due to narrow spaces and fitting of the presenting parts at the pelvic brim II- Flat rachitic pelvis: Features : 1- Forward of the sacral promontory resulting in reduction of the true conjugate 2- Hyperplasia at the junction between sacral vertebra may result in false promontory 3- Divergence of the ischial tubersity and aceteabulum resulting in wide subpubic angle and increased bituveros diameter 4- Contractions occur only at the level of the inlet so if the head possed the inlet there will be more difficulty (single dimensionally contracted pelvis) Mechanism of labour: 1- Head engagement in the transverse diameter 2- Asynclitism with anterioer porful bone presentment 3- Lateral displacement of the head to bring the short biterporal diameter in the short true conjugate 4- Deflection occurs with descent 5- With further descent both asynclitism and deflection are corrected 6- rotation (2/3 circles) interiorly because the outlet is wide III- Simple flat pelvis: Features : reduced AP diameter of the inlet cavirty and outlet without rachitic stigmata Mechanism of labour: 1- At the pelvis inlet: like flat rachitic pelvis 2- At the outlet there will be: a. Extreme flexsion and moulding (reduced AP diameter at the outlet) b. Increased incidence of perineal lacerations due to backwards dispalecment of the fetal head (narrow) subpubic angle ) c. In OP: deep transverse arrest or face to pubis (short posterior rotation) IV – Funnel pelvis (contracted outlet) Causes: 1- 20% if generally contracted pelvis 2- Android pelvis 3- High assimilation pelvis 4- Spreadylo lithesis: sublaxation of the 5the labour in front of the sacral promontory resulting in downwards and backward displacement of the sacrum deep, cavity and increased inclination of the plane of the inlet and some cases may show outlet contraction resulting in funneling 5- Lunbodacrel kyphasis 6- Obliquely contracted pelvis 7- Some cases of richets & asteomalacia Mechanism of labour : 1- Extreme flexion & moulding at the outlet 2- Backwards displacement of the head due to narrow subpubic angle resulting in increased incidence of perineal laceration 3- In OP: deep transverse arrest or face to pubis Diagnosis of CP I- History 1- post history of trauma or disease that cause pelvic contractions eg Rickets osteamalacia, poliomyelitis TB fractures or thopedic surgery 2- Bad obstetric history Malpresentation repeated fetal losses and operative deliveries II- Examination: 1- General: a. Short stature b. Rachitic manifestation c. Abnormal gait (eg limbing waddling) 2- Abdominal (during pregnancy) a. Pendulous abdomen b. Scar of CS c. Malpresntation face brow shoulder presentation d. Non engaged head in last 2w of pregnancy in primigravida III- Investigation: 1- Pelvimetry : a. Clinical pelvimetry b. MRI c. Radiographic pelvimetry (x-ray CT) d. Sonographic cephalometry Cephalopelvic disproportion test Pelvimetry I- Clinical Pelvimetry 1- External Pelvimetry of the inlet 2- External Pelvimetry of the outlet - Subpubic angle (normalley 90) - measured by fingers or morris disc - normally the angle can accommodate two fingers near the apex - Bituberous diameter (normally 11Cm) : - measured by pushing the knuckles of the 4 fingers or closed first between ischil tuberosities or by pelvimeter (Thom's crossing pelvimeter) - normally this diameter can accommodates the closed first or the knuckles of the 4 fingers easily 3- Anteroposterior diameter of the outlet normally 13cm - Measured by 2 fingers in the vagina by the same method used fordiagnal conjugate 4- Posterior and anterior sagittal diameter of the outlet (normalley 102 cm) measured by Thom's pelvimeter Thom's diction: for spontaneous vaginal delivery to occur the sum of the transverse and posterior diameter of the outlet must be > 15cm NB: pelvic outlet is accessible clinically so obstetrician must not be surprised by outlet contraction during labour outlet contraction must be diagnosed during pregnancy or very early in labour in the first exam. Internal pelvimetry : - Usually done after 36 weeks - Patient in lithotomy position without anesthesia by the gloved rt hand 1- Diagnosed conjugate (normally 12-15cm) - tip of rt middle finger reaching the sacral promontory mark the point that impringes on the lower border of the symphsis pubis on the radial border of the rt index - withdraw the rt 2 fingers and measure the distance between the tip of the middle finger and that point by a ruler NB: the same method is used to measure the anetroposteriorer diameter of the outlet but tip of middle finger touches the tip of sacrum 2- palpatic the shape of the sacrum normally it is broad with cancer or flat anterior surface 3- palpable the two ischial spines and approximate distance between them : normalley it is felt not prominent or undeuley projecting with the distance between them > 10.5cm 4- palpable the coccyx: normally is mobile and can recedes back wards easily 5- palpable the sacroscpinous ligaments normally it is 2 fingers breadth (3.5cm) 6- palpable side walls of the pelvis and sacroscietic notch - normalley parallel or divergent walls with wide notch 7- the anteroposterior diameter of the pelvic outlet - Measured by the same manner as diagonal conjugate Radiological pelvimetry A- Plain x-ray: - for borderline cases of pelvic contraction 1- lateral pelvimetry is the best to be done during labour look for the following an lateral fibm - Pelvic inclination (angle between the true conjugate and anterior surface of lunbar ureterbea ) - sacral promontory (jutting or not ) - length and shape of the sacrum - sacroscitic notch (wide or narrow) - level of the head in rotation to the ischial spine - true conjugate and posterior sagital measured by a ruller after putting a scale on the film 2- inlet and outlet radiological pelvimetry is of less importance x-ray pelvimetry is of little value in cephalic presentation (clinical cephalopelvic disproportion tests are more valuable ) CT : Advantages : 1- reduced radiation exposure 2- greater accuracy and easier technique MRI : Advantages : 1- no ionizing radiation 2- accurate measurement 3- complete fetal and placental imaging 4- evaluation of soft tissue dystocia Disadvantages: 1- cost 2- time factor 3- equipments availability Cephalopelvic disproportion tests If the head is not engaged in the last 2 weeks of pregnancy CPD is suspected and can be tested by the following maneuovers in which the fetal head is used as a pelvimeter 1- Pinard's maneuver: a. The women is examined in the seminstting position to coorect pelvic inclination (the oasis of the fetus and the uterus becomes perpendicular to the brim b. The head is grasped by the left head and pushed steadily in the pelvis c. The fingers of the rt hand is in front of the symphesis pubis to determine whether the head is engaged or not and degree overlap of the head on the symphsis pubis 2- Pinard's –Muller – Kerr's bimanual maneuver: a. The women on her back with the head and shoulder slightly abducted b. The left hand described in pinard's maneuver . the idea and middle fingers of the rt hand inside the vagina to note the degree of descent of the fetal head in relation to the ischial spine and the angle between the head and posterior surface of the symphesis pubis c. If the head is not engaged the throuth of the rt hand is placed on the sympysis pubis to note any overlap of the head over it d. Gentle fundle pressure by an assistant may be helpful e. If no CPD exists the head readily enters the pelvis and vaginal delivery can be predicted f. Inability to push the head into the pelvis doesn’t necessarily indicate that vaginal delivery is impossible g. if the head flexed head overrides the symphysis pubis this will be a presumptive widen of disproportion Degrees of CP and CPD CP CPD Minor degree Minor AP diameter 9-10cm No actual CPD because uterine contractions and pelvic reserve compensate this minor degree of contraction and vaginal delivery is the rule if no associated complication The a anterior surface of the head is in line with the posterior surface of the symphysis pubis flushing of the head with the S-pubis) with contraction during labour the head is engaged Moderate degree 1st degree CPD (moderate disproportion) - AP diameter 8-9cm - Resulting I CPD - Great majority of cases of CP - Difficult to predict its outcome so managed by trial labour and CS if failed - The anterior surface of the head is in line with the anterior surface of the symp pubis (overriding of the head with symphsysis pubis) - During labour sufficient moulding and uterine contraction may allow vaginal delivery (trial of labour if failed CS) Major degree 2nd degree CPD (severe disproportion) - AP diameter 6-8cm - Results in 2nd degree CPD - With living fetus CS is absolutely indicated - With dead fetus craniotomy can be tried if experienced obstetrician is available Extreme degree - AP diameter<6cm - Correspond also to 2nd degree CPD but CS is done even with dead fetus because the AP diameter is less than the smallest diameter of the head (Bimostoid which equal 7.5cm) so the problem cant's be solved by any destructive opeartiation (even the cronioclost and cephalo tribe) - The head is projecting beyond the anterior surface of the symphesis pubis (overriding head) - Vaginal delivery of living baby is impossible and CS is the rule - Corresponds to both major and extreme degree of CP but with dead fetus craniotomy is tried in major degree and CS is the only line in extreme degree Summary : - Mild (minor ) degree CPD corresponds to minor degree of CP : spontaneous vaginal delivery is the rule forceps may be needed for short ening of the 2nd stage of labour - Moderate degree (1st degree) CPD corresponds to moderate degree CP : trial labour if failed CS - Severe degree CPD (2nd degree) corresponds to major and extreme of CP : CS is the rule for living babies. For dead babies craniotomy is trial in major degree only if trained obstetrician is available and CS is done in extreme degree even with dead baby

1 comment:

  1. شكرا جزيلا دكتور علاء ع فكرة موقع جميل جدا ومفيد ونتمني الاستفادة منه بجد قدر المستطاعد
    وحضرتك بجد هتفيدنا كتير سواء ف الراوند او هنا
    طالب بالراوند بتاعك
    محمد سعد
    شكرا اغلي دكتور علاء