Abstract
While 50% of cases of inversion of the uterus have no identifiable risk factors [5], mismanagement of the third stage (applying traction on the umbilical cord before contraction of the uterus and applying fundal pressure) is considered as the prime cause [3].Other recognised predisposing factors include uterine atony, fundal implantation of a morbidly adherent placenta, manual removal of the placenta, precipitate labour, a short umbilical cord, placenta praevia and connective tissue disorders (Marfan syndrome and Ehlers–Danlos syndrome) [3]. It has also been reported to follow sudden increases in intra-abdominal pressure such as coughing or, sneezing before contraction of uterine muscles, delivery of a baby with cord around the neck, giving birth in sitting or erect position, precipitated labour [4] and very rarely during caesarean section [1]. Even though individual risk factors do commonly occur, rarity of the condition indicates that these factors must act in unison to culminate in an inversion of the uterus.
Key Facts
Acute puerperal uterine inversion is a rare, potentially life-threatening complication of pregnancy. It usually follows vaginal delivery but, very rarely, it may follow caesarean section [1]. It is defined as ‘the turning inside out of the fundus into the uterine cavity’ [2]. It may occur either before or after the delivery of the placenta.
Its incidence is quoted between 1 in 2000 to 1 in 23 000 pregnancies [3]. It is estimated that most maternity units in the United Kingdom would experience one uterine inversion once in every decade [3]. The incidence may be higher in developing countries.
Since its reported mortality rate could be as high as 15% and because it may occur suddenly and unpredictably, it is imperative that every practitioner providing maternity care is familiar with the management of this potentially catastrophic event. However, due to its rarity, it is unlikely that obstetricians would be able to become experienced in its management. Successful management is largely dependent on accurate diagnosis but its rarity and variation in the severity of clinical features may allow it to go undetected in its initial phases [4]. Failure to institute prompt treatment could lead to haemorrhage, rapid development of shock, and death.
Aetiology
While 50% of cases of inversion of the uterus have no identifiable risk factors [5], mismanagement of the third stage (applying traction on the umbilical cord before contraction of the uterus and applying fundal pressure) is considered as the prime cause [3].Other recognised predisposing factors include uterine atony, fundal implantation of a morbidly adherent placenta, manual removal of the placenta, precipitate labour, a short umbilical cord, placenta praevia and connective tissue disorders (Marfan syndrome and Ehlers–Danlos syndrome) [3]. It has also been reported to follow sudden increases in intra-abdominal pressure such as coughing or, sneezing before contraction of uterine muscles, delivery of a baby with cord around the neck, giving birth in sitting or erect position, precipitated labour [4] and very rarely during caesarean section [1]. Even though individual risk factors do commonly occur, rarity of the condition indicates that these factors must act in unison to culminate in an inversion of the uterus.
Key Implications
A dilated cervix with a relaxed uterus and simultaneous downward traction on the fundus are the possible factors leading to inversion of the uterus [6]. Ensuring proper retraction of the uterus prior to applying traction on the cord would therefore be the primary factor that prevents acute inversion of the uterus. There are many accounts of uterine inversion in the literature from times when fundal pressure was the method used for expulsion of the placenta [7]. Thus, the introduction of active management of the third stage of labour has been a major contributor to the current low incidence of this condition [6].
The inverted fundus becomes trapped within the cervix, creating progressive oedema and congestion due to interruption of venous and lymphatic drainage [3]. This becomes a vicious cycle and the longer the time elapsed since inversion, the more difficult repositioning of the uterus.
As the inversion progresses, the round and infundibulo-pelvic ligaments and ovaries become indrawn into the inverting uterine fundus, which forms a depression in it. The extent to which the ligaments and ovaries get drawn into it will obviously depend on the degree of inversion. The in-drawing of the peritoneum, the ligaments and the ovaries will result in significant pain and stimulation of the autonomic nervous system, resulting in the neurogenic shock which accounts for the picture that is typical of the early course of the condition. The degree of shock observed is out of proportion to the bleeding that is observed [8]. Significant haemorrhage due to poor retraction and congestion of the inverted uterus and partial separation of the placenta will follow and amplify these effects [8].
Key Diagnostic Signs
Inversion of the uterus is classified according to the time elapsed from the time of birth [9] and depending on how far the fundus of the uterus has inverted [4], as shown in Table 18.1.
Table 18.1 Classification of inversion of the uterus
| Classification of acute inversion of uterus | |
|---|---|
| According to time of onset | |
| Acute | Within 24 hours of birth |
| Subacute | Between 24 hours and 4 weeks after birth |
| Chronic | Any time after 4 weeks of birth or in a non-pregnant woman |
| According to degree of descent | |
| First degree | Fundus is inverted but is above the internal os |
| Second degree | The fundus has extended beyond the os but remains within the vagina |
| Third degree (complete inversion) | Fundus extends to or beyond the introitus |
| Fourth degree | The vagina has also inverted along with the uterus |
First- and second-degree inversions are referred to as incomplete inversion, while third- and fourth-degree inversions are referred as complete inversion. The second-degree uterine inversion is the most common presentation [6].
Key Pointers
The diagnosis of uterine inversion is based on clinical findings. In its most dramatic presentation, it is seen or felt as a uniform lump appearing at the introitus with the cervix felt around its base. The placenta may or may not be attached to the mass. Initially, the inversion may feel to palpation like a fetal head and appear as a pinkish-white mass. With time the mass will become oedematous and bluish in colour [4].
When there is complete inversion, the diagnosis is most easily made by palpating the inverted fundus at the cervical os or vaginal introitus and the uterus being impalpable abdominally. In incomplete inversion, the uterus may appear to be normal or a fundal dimple may be palpable if the woman is thin.
However, the vast majority of the cases present with haemorrhage (94%) with or without cardiovascular collapse [10]. Blood loss depends on the inversion–reversion interval and can lead to serious haemodynamic instability [11].
Typically, shock appears early and initially this is neurogenic, producing signs that are out of proportion to the severity of blood loss. However, within a short period of time marked haemorrhage ensues, leading to hypovolaemic shock [1, 3]. Acute inversion of the uterus must be excluded in all cases of postpartum collapse with or without haemorrhage.
Ultrasound could be misleading, since the apposed serosal surfaces of the of the invaginated uterine walls could appear as an empty endometrial cavity.
Severe and sustained hypogastric pain in the third stage of labour, profuse bleeding, absence of the uterine fundus with or without an obvious defect of it on abdominal palpation, as well as evidence of shock with severe hypotension are important diagnostic clues which point to a diagnosis of uterine inversion [11].
Key Actions
Early diagnosis, early involvement of experienced personnel, and teamwork play a major role in the successful treatment of uterine inversion. Management of shock and repositioning of the uterus as soon as possible are the key aims of management. These must be pursued aggressively and run concurrently [3]. Delays would result in progressive oedema of the inverted uterus and its entrapment within the cervix, a combination that is self-propagating and one that makes repositioning increasingly difficult.
Adherence to basic principles of managing an emergency situation (calling for help, multidisciplinary approach, etc.) will improve the outcome. An algorithm for management of acute puerperal uterine inversion is provided in Figure 18.1.
Figure 18.1 Algorithm for management of acute puerperal uterine inversion.
Management of Shock
While the cause of the initial shock is neurogenic (bradycardia, hypotension), hypovolaemic shock will ensue due to haemorrhage [12]. Some studies quote the incidence of postpartum haemorrhage to be as high as 94% [10], with an average blood loss of about 1250 mL [9]. Aggressive resuscitation is needed. Resuscitation of an obstetric patient is described in Chapter 2 in this volume.
Repositioning of the uterus is the best way to manage the neurogenic component of an acute inversion. Providing adequate analgesia while this is being attempted would help mitigate some effects of vagal stimulation.
Repositioning of Uterus
Non-surgical Methods
Manual Replacement of the Uterus
Manual repositioning of the uterus should be attempted without delay as soon as the diagnosis is established. This first-line procedure which is commonly used for repositioning of the uterus is ‘Johnson’s manoeuvre’, first described in 1949 [13]. The rationale behind this manoeuvre is that lifting the uterus into the abdomen will increase tension on the ligaments, causing the uterus to reposition itself.
The operator introduces two-thirds of the forearm into the vagina and extends the hand at the wrist to place the palm on the inverted fundus and fingertips at the utero-cervical junction. Lifting the uterus above the level of the umbilicus creates adequate tension for the cervical ring to dilate and for the fundus to revert to its normal position. The chance of successful repositioning is between 43% and 88%, with early commencement of attempts resulting in higher success rates [3].
The uterus should be held in position for a few minutes after reduction and uterotonic drugs should be administered to aid contraction of the uterus and thus prevent reinversion. Administration of an appropriate antibiotic is advised [3].
The placenta should be removed only after repositioning of the uterus and complete correction of the inversion, in order to avoid shock from torrential bleeding [8]. With delay, the formation of a contraction ring and oedema of the entrapped portion of the uterus will make the procedure more difficult, resulting in more bleeding .
If this initial method fails or cannot be performed due to an already oedematous uterus entrapped in a cervical ring, hydrostatic reduction should be attempted, ideally in an operating theatre.
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