The definition of an ectopic pregnancy is a pregnancy outside the uterine cavity, not outside the uterus, as the interstitial pregnancy is still a uterine pregnancy. Diagnosis
Early diagnosis is important and today facilitated by the use of sonography and the quantitative human chorionic gonadotropin (hCG) assay. As in other cases of ectopic pregnancy, risk factors are:  previous tubal pregnancy, IVF therapy, tubal surgery, and a history of sexual infection. Typical symptoms of an interstitial pregnancy are the classic signs of ectopic pregnancy, namely abdominal pain and vaginal bleeding. Hemorrhagic shock is found in almost a quarter of patients. ; this explains the relatively high mortality rate. In pregnant patients, sonography is the primary method to make the diagnosis, even when patients have no symptoms. The paucity of myometrium around the gestational sac is diagnostic, while, in contrast, the angular pregnancy has at least 5 mm of myometrium on all of its sides. Ultrasonic criteria for the diagnosis include an empty uterine cavity, a gestational sac separate from the uterine cavity, and a myometrial thinning of less than 5 mm around the gestational sac; typically the interstitial line sign—an echogenic line from the endometrial cavity to the corner next to the gestational mass—is seen. MRI can be used particularly when it is important to distinguish between an interstitial and angular pregnancy. On average, the gestational age at presentation is about 7–8 weeks.
Callosities arise naturally and are present even in late-term whale fetuses, although the work of lice digging into the surface of the skin may make them more jagged and hard over time.Callosities are found on the upper surface of the whales head, above the eyes, on the jawline and chin and surrounding the blowholes. Callosities form a unique pattern on every right whale and though callosities which are overgrown break off, the patterns do not change over a lifetime. This makes them a very useful tool for the purposes of photo-identification and conservation.The evolutionary significance of callosities is unknown. Male right whales have a higher density of callosities than females. Males have been observed scratching one another with their callosities and it has been suggested by Payne & Dorsey (1983) that they are a sexually dimorphic feature, used for intra-specific sexual aggression. That explanation is not entirely satisfactory, because it does not account for the appearance of callosities in females. It has been proposed that the barnacles attached to callosities are important in helping fend off attacks by orcas. See also
Callus

Notes
References
Steudel, K (1981). "Functional Aspects of Primate Pelvic Structure: A Multivariate Approach" (PDF). American Journal of Physical Anthropology. 55 (3): 399–410. doi:10.1002/ajpa.1330550314. PMID 6791507. Archived from the original (PDF) on 2010-06-10. Retrieved 2009-07-19. Callosities by Mason T. Weinrich in the Encyclopedia of Marine Mammals. ISBN 0-12-551340-2. A Dictionary of Zoology 1999, Oxford University Press 1999
"On Butts and Baboons". Artsibasheva, A.  http://monkeybuiznezz.wordpress.com/2012/09/27/on-butts-and-baboons/