Heard someone you know had a uterine rupture? Sounds like a nightmare? Want to know everything about it? Before you read further you must know that yes it is scary but it is a very rare condition and that though you may have one or more risk factors that are mentioned below the chance that you might face this are low. Studies show that a majority of women who deliver after a prior caesarean, have a safe and normal birth. According to the National Health Institute, 992-993 women out of 1,000 give birth without the complication of a uterine rupture.
What is Uterine Rupture?
Uterine rupture or a tear in uterine wall during pregnancy is a very rare complication observed in the last trimester of pregnancy which can cause maternal and foetal distress.
The uterus is a stretchable bag-like structure located in the abdominal cavity and it’s wall is 3 layers thick.
- The inner thin layer is called the endometrium. It is the most active layer responding to all the hormonal changes and is highly specialised.
- The middle layer is a thick layer of muscles which forms the main bulk and it gives the strength to the wall of the uterus.
- The outermost layer called the serosa or the peritonium is a very thin layer which forms a coat or an envelope and hence separates the uterus from the abdominal cavity.
Uterine rupture occurs when the uterine wall is disrupted in such a manner that the contents of the uterus (like the foetus, the placenta, and the umbilical cord) can be expelled into the abdominal cavity.
On the other hand, uterine scar dehiscence or uterine window or scar separation involves the disruption and separation of a pre-existing uterine scar and it does not disrupt the serosa. Hence the contents of the uterine cavity remain within the uterus.
Uterine scar dehiscence is far more common than uterine rupture and only rarely results in major maternal or foetal complications. Although a uterine scar is a well-known risk factor for uterine rupture (most of which arise from prior cesarean delivery), the majority of the events involving the disruption of uterine scars results in uterine scar dehiscence rather than uterine rupture. These two conditions need to be clearly distinguished, as the clinical management and the resulting clinical outcomes differ significantly.
Uterine Rupture & Pregnancy
Uterine rupture usually occurs during peripartum, that is the time period shortly before, during, and immediately after delivery. This is obviously because it is the time when the foetus has attained maximum size and the uterus is maximally stretched. It can either occur in women with a native, unscarred uterus or a uterus with a surgical scar from previous surgery done for any reason – previous Cesarean section or any other surgery like a myomectomy (partial removal of diseased uterine wall be it by open surgery or a laparoscopy).
What are the Chances of Uterus Getting Ruptured?
Even in high-risk groups, the overall incidence of a ruptured uterus during delivery is quite low. It occurs at the rate of 1 in 1,146 pregnancies (0.07%). The chances of uterine rupture are even fewer in an unscarred uterus. But if you have undergone a previous Cesarean section or any surgery on the uterus, the risk of a uterine rupture during delivery doubles consequently. Also, higher the number of various risk factors present, more is the chance of rupture, the incidence still being very low.
What are the Risks for a Uterine Scars Separation?
The possible causes of uterus rupturing are different for an unscarred uterus and a scarred uterus, the later being accountable for most of the cases.
Reasons for Uterine Rupture in an Unscarred Uterus
Unscarred uterus is least susceptible to a uterine rupture. The incidence is only 0.012% that is 1 in 8434 pregnancies – almost all the cases being those of second or third pregnancies rather than first pregnancies. So if this is your first delivery and if you have never had any surgery done on your uterus, you need not worry.
Following are the risk factors in an unscarred uterus:
- Grand multiparty (several pregnancies): Studies say that the chance of rupture is more if there have been more than 3 deliveries in the past. In successive deliveries there is a progressive thinning of the uterine wall and hence the risk increases.
- Obstructed labor: This occurs when a woman is allowed to go in labour (known as trial of labour) in order to have a natural vaginal delivery, but the labour is aborted and a C-section is performed to complete the delivery. Doctors typically take this decision is the birth canal is too small for the baby to be born.
- Neglected labor:This usually happens when there is no access to medical care, or in case of home-births.
- Malpresentation: In this case, a different body part of the baby appears first during the birth instead of the head. Usually the head is the ‘presenting’ part of the baby being born, however sometimes the child’s presenting part is the hip or the shoulder or the face or the legs. This causes abnormal and uneven pressure over the uterus which then gives away
- Uterine instrumentation by the doctor during a difficult labor (such as use of forceps) may cause uterine ruptures.
- Labor induction or augmentation using oxytocin (drug used to increase uterine contractions) can increase chances of uterine ruptue.
- Congenital abnormality of the uterus
Reasons for Uterine Rupture in a Scarred Uterus
A single cesarean scar increases the overall rupture rate to 0.5%, with the rate for women with 2 or more cesarean scars increasing to 2%. Medical literature suggests that there is an increase in the complications following vaginal birth after previous cesarean section (VBAC) due to uterine rupture. This and the medico-legal fears is the reason why there is a decline in the doctors offering and women accepting planned VBAC in the UK and North America and now also in urban India. Can uterine fibroids rupture? Well, the scar of myomectomy on the uterus (the surgery done to remove the fibroids) can give way to uterine rupture. The fibroids per se causing rupture in unscarred uterus is extremely rare.
Risk factors in a scarred uterus:
1. Trial of Laboru after Previous C-Section (TOLC)
There is 3.3. fold increased risk of spontaneous uterine rupture after previous C-section compared with women who undergo elective repeat cesarean delivery. But it is quite interesting to note that if there has been one successful VBAC (vaginal birth after C-section) earlier, the chance of uterine rupture during VBAC subsequently is decreased.
Multiple potential theories exist, but the 2 most obvious are that a successful prior VBAC attempt ensures that –
- The maternal pelvis is tested and is adequate to permit passage of the fetus
- The integrity of the uterine scar has been tested previously under the stress/strain conditions during labor and delivery that were adequate to result in vaginal delivery without prior uterine rupture.
2. Type of C-Section Scar
The upper vertical scar in olden times is now almost obsolete as it carried maximum risk of rupture. The lower transverse scar most commonly used today is least susceptible to rupture.
3. Interdelivery Time Interval
There is a 3 fold increased risk of a rupture if the interdelivery time between the previous C-section and the subsequent delivery is less.
4. Maternal Age
There is a 3 fold increase in the rate of rupture if the maternal age is > 30 years compared to younger mothers
There is no increased in twin pregnancy compared to singleton pregnancy.
6. Size of the Baby
There is a slightly higher risk of rupture if the weight of the baby is more (> 4000 gms)
7. Advanced Gestational Age
There is significantly higher risk of rupture if the gestational age is > 40 weeks as usually they are associated with induction of labor.
Signs & Symptoms of Uterine Rupture
What happens if scar starts to tear during labor? The initial signs and symptoms are quite nonspecific and that makes the diagnosis difficult, delaying the definitive treatment. The signs and symptoms may vary from being minimal like in a small dehiscence to a severe life threatening one, like in case of a large rupture which involves a major blood vessel. It largely depends on the timing, site, and extent of the uterine defect. Uterine dehiscence at the site of a previous uterine scar is typically serious because the scar has relatively fewer blood vessels.
Symptoms: What the Mother Can Experience?
A mother when in labor or due to lack of experience may not be able to notice any symptom and hence delay the diagnosis and treatment. Following are some symptoms that may indicate a uterine rupture:
- Abdominal pain: Sudden or a sharp pain which the mother can differentiate from normal labor pain only if very alert and informed. This pain persists even between the contractions. A woman undergoing a painless delivery under a spinal anaesthesia will not feel the pain. Thus, abdominal pain is an unreliable and uncommon symptom of uterine rupture.
- Can no more feel the uterine contractions or lesser intensity contractions
- Sharp onset of pain at the site of the previous scar
- Excessive vaginal bleeding
- Giddiness and loss of consciousness
Signs: What a Doctor Can Pick Up?
- Foetal distress: The most common sign and often the first and only sign of uterine rupture, is abnormalities in foetal heart rate as measured by electronic foetal monitor. This sign is usually present in 79-87% of patients. Hence it is very important for the doctor to monitor the foetal heart rate when a mother is undergoing labour.
- Diminished baseline uterine pressure
- Recession of the presenting foetal part: A baby may sometimes slide back into the uterus as the uterus can no longer push the baby outwards (on account of getting ruptured).
- Excessive vaginal bleeding
- Shock: This will occur after there is lot of blood loss and drop in the blood pressure.
These signs are not specific for uterine rupture but only indicative and needs a proper diagonisis by experts.
What Happens If the Scar Starts to Tear during Labour
The consequences of uterine rupture depend on its severity, the time between diagnosis and treatment and the level of medical care available.
Foetal consequences are admission to neonatal intensive care unit, fetal hypoxia or anoxia (decreased or no oxygen to the baby respectively), and neonatal death. The chance of death varies from 6-17% but the incidence of perinatal death associated with uterine rupture is decreasing in the modern era.
Maternal consequences are bleeding, low blood pressure, bladder injury, need for hysterectomy, and maternal death.
Diagnosis of Uterine Dehiscence
Uterine rupture being an emergency needs rapid diagnosis and treatment. Because of the short time available before the onset of irreversible damage, time-consuming diagnostic methods and sophisticated imaging modalities have only limited use. It is only the clinical expertise of the doctor that will help based on the standard signs and symptoms.
One may wonder – is it possible to predict an uterine rupture well in advance and be prepared? It is, but only in selected few cases. Various diagnostic techniques have been used to attempt to assess the individual risk of uterine rupture in selected patients. MRI may aid in evaluating the status of a uterine scar. Ultrasonography may be useful for detecting uterine-scar defects after caesarean delivery by measuring the thickness of the uterus wall. The risk of uterine rupture after previous caesarean delivery is directly related to the thickness of the lower uterine segment, as measured during transabdominal ultrasonography at 36-38 weeks of gestation. The risk of uterine rupture increases significantly when the uterine wall is thinner than 3.5 mm.
Uterine Rupture Treatment for Pregnant Women
The most critical part of the management of uterine rupture is a timely diagnosis and commencement of the treatment as fast as possible. As a rule, the immediate stabilisation of the mother (including fluid resuscitation and blood transfusion) and the delivery of the foetus within 10-37 minutes of uterine rupture is necessary to prevent serious complications to both the mother and the child. The newborn may require an NICU (Neonatal Intensive Care Unit) admission and observation. Later the mother might need a surgical intervention which again may vary from a simple tear repair to removal of the uterus (hysterectomy) depending on the type and the extent of uterine rupture, the degree of bleeding, general condition of the mother and the mother’s desire for future child bearing.
Can Uterine Rupture Harm Baby & Mother?
Yes. Uterine rupture can cause significant harm to mother and the baby. It can also result in death. But in a well-managed case with prompt diagnosis and treatment in a well-equipped hospital, the mother and the baby usually do well and death is an extremely rare occurrence. In some cases uterine rupture recovery time is prolonged and needs longer hospital admission adding to the cost. A uterine dehiscence is less harmful and in fact may not cause any trouble at all.
How Can Uterine Rupture Be Prevented?
The most direct prevention strategy for pregnancy-related uterine rupture is to minimise the risk factors. The risk modification begins even before the first conception until the last delivery.
What can a mother do?
- Plan pregnancy before age of 30 years.
- Don’t opt for a Caesarean section only because you want to avoid the painful labour. Natural is always the best. A c-section scar is not natural.
- Spacing is important. Avoid pregnancy within 2 years of a Caesarean section.
- Be a good patient. Timely consultation as advised by your doctor especially in the last trimester and close to the expected date of delivery helps
- Feel free to consult when something unusual is felt like sudden abdominal pain, loss of contractions, decreased foetal movements, etc.
- Crossed your expected date of delivery and getting labour pain yet? Meet your doctor immediately.
What can a doctor do?
- Identify a patient at high risk of uterine rupture.
- Try to predict the event with the help of ultrasonography or MRI.
- Counsel and inform the mother in detail regarding her condition and help take the best decision.
- Take timely decision about whether to conduct a trial of labour or opt for Caesarean section depending on the risk factors.
- Tight closure of the C-section wound in at least 2 layers and avoiding a single layer stitch should be done.
- Close monitoring of the foetal heart rate and foetal activity is important.
- Prompt diagnosis of the uterine rupture and treatment is crucial too.
Although uterine rupture can have dire consequences, it is important to remember that it is extremely rare, and can be harmless if detected early. Being aware and staying alert are the best ways of avoiding a uterine rupture.