Definition: An ectopic pregnancy occurs when a fertilized egg implants somewhere other than the main cavity of the uterus, most commonly in the Fallopian tubes.
Background:
First descriptions of ectopic pregnancy in England dates back to 1731 when Gifford described implantation of a pregnancy outside the uterine cavity.
Charles Meigs provided particularly vivid descriptions of severe cases of ectopic pregnancy in the mid-nineteenth century, when ectopic pregnancy was considered to be a rare, but universally
fatal condition.
With the improvements in surgical techniques at the turn of the twentieth century ectopic pregnancy became curable . However, it was still considered a very serious problem with high mortality rates. This perception has changed only recently with the increased ability to establish the diagnosis of ectopic pregnancy non-invasively in women with minimal clinical symptoms.
Although there has been a massive increase in the incidence of ectopic pregnancy in recent years, the
mortality of the disease has been static . Therefore the main challenge in modern clinical practice is to identify and treat as early as possible cases of ectopic pregnancy with the potential to cause serious morbidity and death, and at the same time to minimize interventions in those destined to be resolved without causing any harm.
Risk Factors For Ectopic pregnancy:
A number of factors have been identified, which increase individual risk of ectopic implantation.
An association between increased maternal age and ectopic pregnancy has been well documented in the past. The incidence of ectopic pregnancy is three times higher in women aged 35–44 in comparison to those in the age group 15–24.
A past history of sexually transmitted disease also increases the risk of ectopic pregnancy.
A list of the risk factors associated with increased chances of ectopic pregnancy is given below:
- History of previous ectopic pregnancy
- (IUCD) or sterlization failure
- Pelvic inflammatory disease
- Chlamydia infection
- Early age of intercourse and multiple partners
- History of infertility
- Previous pelvic surgery
- Increased maternal age
- Cigarette smoking
- Strenuous physical exercise
- In utero DES exposure
Pathophysiology
In normal pregnancy the egg is fertilized in the Fallopian tube, and then it is transported into the uterus to be implanted. If the fertilized egg implants at any other place other than the uterus (most commonly in the fallopian tubes) it leads to ectopic pregnancy.
Any abnormality in tubal morphology or function may lead to ectopic pregnancy. It is believed that the most important cause of ectopic pregnancy is damage to the tubal mucosa, which could obstruct the embryo transport due to scarring.
The other possibility is that a small defect in the mucosa attracts implantation in the Fallopian tube.
The mucosal damage may be caused by infection or surgical trauma.
In some women the cause of ectopic pregnancy may be a dysfunction in the tubal smooth muscle activity.
An altered oestrogen/progesterone ratio may affect tubal motility in different ways. Abnormally
high oestrogen levels may cause tubal spasm, which could block transport of the embryo towards the uterine cavity. This may be an explanation for increased rates of ectopics following ovarian hyperstimulation and post-coital oral contraception.
Conversely, pharmacological doses of progesterone in women using progesterone-only contraception
could cause complete tubal relaxation leading to retention of the fertilized egg within the tube.
Embryonic abnormalities have also been studied in an attempt to explain occurrence of ectopics in the absence of tubal pathology and although the majority of tubal pregnancies are non-viable, the incidence of chromosomal defects is no higher than in samples obtained from intrauterine pregnancies.
Clinical Presentation
The clinical presentation of ectopic pregnancy is very variable and reflects the biological potential of pregnancy to develop beyond a very early stage. This in turn is largely determined by the location of pregnancy within the tube. In general, more proximal implantation to the uterine cavity shows more advanced development.
Ampullary ectopics, which represent 70% of all tubal ectopics, rarely develop beyond a very early stage and clinical symptoms of tubal abortion may be present as early as 5 weeks gestation.
On the other hand one third of interstitial tubal ectopics develop in a similar way to healthy intrauterine pregnancies with evidence of a live embryo on ultrasound examination. These pregnancies tend to be clinically silent until sudden rupture occurs.
Most ectopic pregnancies represent a form of early pregnancy failure and the first symptom is usually brown vaginal discharge, which starts soon after the missed menstrual period. However, the amount of bleeding varies and in some women it can be quite heavy.
Abdominal pain is usually a late feature in the clinical presentation of ectopic pregnancy. The localization of pain is not specific and it is not unusual for women to complain of pain on the side contralateral to the ectopic. Some women may complain of period-like pain or upper abdominal discomfort. The pain is usually caused by tubal miscarriage and bleeding through the fimbrial end of the tube into the peritoneal cavity. The pain varies in intensity and does not necessarily reflect the volume of blood lost inside the abdominal cavity.
Pain associated with rupture tends to be more intense, with signs of peritonism on abdominal palpation. Severe rupture sometimes presents with nausea, vomiting and diarrhea, which may resemble a gastrointestinal disorder. This confusing picture may cause a delay in the diagnosis of ectopic pregnancies.
Significant intraabdominal bleeding, however, can be recognized by the typical signs of hemorrhagic shock, which include pallor, tachycardia, hypotension and oliguria.
Diagnosis:
A physical exam alone usually isn't enough to diagnose an ectopic pregnancy. Traditionally the diagnosis of ectopic pregnancy was made at surgery and then confirmed on histological examination
following salpingectomy. With the advent of diagnostic ultrasound and the increasing use of conservative treatment, the diagnosis of ectopic pregnancy is increasingly made without the help of
surgery.
Transvaginal scanning provides much clearer images of pelvic structures in comparison to transabdominal scanning. In experienced hands, transvaginal ultrasound will detect 75–80% of clinically significant tubal ectopic at the initial examination.
Morphology Of Ectopic Pregnancy
The morphology of ectopic pregnancy can be classified into five categories:
- gestational sac with a live embryo
- sac with an embryo but no heart rate,
- sac containing a yolk sac,
- an empty gestational sac and
- solid tubal swelling.
The first three morphological types are very specific and enable a conclusive diagnosis of an ectopic to be made. The potential for false positive diagnosis is higher when the sac is empty or in cases with an inhomogeneous tubal swelling
Serum human chorionic gonadotropin (hCG) measurements have traditionally been used as a secondary investigation in women with suspected ectopic pregnancy in whom ultrasound examination has failed to identify an intrauterine or ectopic pregnancy. Abnormally slow rise in serum hCG has also been used to diagnose ectopic pregnancy.
Management
Surgery has been traditionally used both for the diagnosis and treatment of ectopic pregnancy. In the second half of the twentieth century laparoscopy was mostly used as a diagnostic tool and open surgery was used to treat ectopic pregnancy.With recent advances in operative laparoscopy, the minimally invasive approach has also become accepted as the method of choice to treat most tubal ectopic pregnancies. There are important advantages of laparoscopic over open surgery which include
less post-operative pain, shorter hospital stay and faster resumption of social activity.
Medical management of ectopic pregnancy has grown in popularity in recent years following several observational studies which reported success rates with a single dose systemic methotrexate.
Selection criteria for conservative management of ectopic pregnancy
- Minimal clinical symptoms
- Certain ultrasound diagnosis of ectopic
- No evidence of embryonic cardiac activity
- Size <5 cm
- No evidence of haematoperitoneum on ultrasound scan
- Low serum hCG (methotrexate <3000 IU/l; expectant <1500 IU/l)
There are risks and side effects of using methotrexate and therefore patients needs a close followup.
Expectant management has important advantages over medical treatment as it follows the natural history of the disease and is free from serious side effects of methotrexate.
Expectant management requires prolonged follow-up and it may cause anxiety to both women and their carers. However, the main limiting factor in the use of expectant management is the relatively high failure rate and the inability to identify with accuracy the cases that are likely to fail expectant management.
Prognosis:
Fertility after ectopic pregnancy
Intrauterine pregnancy rates following ectopic pregnancy range between 50 and 70% .
Recurrent ectopic pregnancies occur in 6–16% of women with previous history of ectopics and these women should be offered early scans in all future pregnancies to detect recurrent ectopics before complications can occur.
Mortality
Ectopic pregnancy remains an important cause of maternal mortality worldwide. It is seen most commonly in women with the most serious forms of ectopic pregnancies, such as interstitial ectopics, who are typically asymptomatic until sudden rupture accompanied by a massive internal bleeding occurs which can lead to death.
No comments:
Post a Comment